Got into this thread a little late, so pardon my excessive quoting!

I have kept them in the past but never bred them though I imagine it would be similar to other explosive breeders. Typical methods will get amplexus.
Yes, that has been clear with many species. Getting males to call and have them amplex is easy (often just misting them or tossing them into the rain chamber). The issue has been cycling the females so they have eggs, and then getting them to lay. I would be very interested in cycling and laying information that you have - there isn't really anything out there about it in captivity

They are not terribly hard to keep and are able to eat quite large food items for their size.
Could you be more descriptive of their set up and feeding preferences? Short of letting them dig, having a water bowl, and feeding them commonly available food items, particular notes are lacking. Many people have kept them alive for a while, but we're trying to determine what would have them thrive and breed. I'm not sure how tossing them in coco fiber (moist? dry? moist area and dry side? no one says!) with a water bowl is the healthiest thing for them. The IUCN seems to think that one of the reasons they have such a demand for export is because "the high level of mortality among captive animals might be contributing to the high level of trade". If you can help us change that, please share!

I believe they are now considered "critically endangered" primarily due to localized habitat but are not particularly rare or uncommon within that habitat. As long as they are not heavily over collected( and with the quotas now in place I don't think that is a serious issue) or the habitat somehow destroyed(which is always possible in Madagascar) I suspect they will be able to sustain the current level of importation indefinitely or until political issues change importation laws.
I recommend reading the Scaphiophryne gottlebei species profile on the IUCN Red List website. This is one of the few species that actually lists over-collection for the pet trade as a major threat, and listed as the FIRST major threat, not as one mentioned in passing. They are even talking about the LEGAL pet trade, not even implying smuggling. This was how they were assessed in 2008 - when they had a limited export quota of 1000 since at least 2005! To add insult to injury, the whole area they exist in is under threat due to habitat destruction and modification both in and surrounding their range (only part of which is protected - but even the protected areas are being influenced by the areas around them). Mantella expectata (which is from the same area, though more at the entrance to the canyons than the canyons themselves) also has the same threats listed in their IUCN profile, but they mention "It is actively sought after for the pet trade, and during the rainy season up to several thousand specimens can be collected. Such collecting might pose a major threat to the species, but this has not, as yet, been demonstrated." This was the SAME ASSESSMENT that was done for S. gottlebei, which means when they talk about the pet trade as a threat in the Hopper profile, it's a demonstrated influence!

As Eric mentioned, in talking on another thread I brought up their 2010 quotas - just 250 for the WORLD. It's a very small step to go from 250 to 0, and it could be heading that way.

I'm sorry to harp on this, but that statement was really aggravating to me! They have been treated as disposable, people have been getting pissed off at their prices going up, and no one seems to care about the reasoning - and I can't stand the idea of people continuing to think that the statement you made was true. The experts that work with this species disagree.

You might talk to "poison beauties" about them and see if he has got anywhere, last fall if I recall I think he was saying he was getting twenty or so and was going to try to breed them though I assume he has not done so(the breeding part anyway). I remember a year or two ago this was one of the species that a number of TWI/ASN members were talking about and were going to attempt to breed and start up a "species management plan" for. I don't think any of them have had any breeding success at this time though since I haven't seen any CB specimens or heard any more about it.
I believe we would have heard about it. Evidently the founder stock for the project didn't come through, and I'm unsure of the standing of the project right now (I really should renew my TWI membership....). It's a project I'd love to get in on, but the lack of animals is causing an issue. I don't check KS for them everyday, and after they broke up the amphibian classifieds I wasn't sure where they'd end up anyways. At least one zoo was concentrating on a breeding project of them, but I've not heard if that has been successful either. Lack of frogs isn't helping, but them not being CB isn't from lack of trying either.

I tend to figure the ones in the hobby are legit as the prices while high are not high enough nor is the demand great enough for most importers to risk being caught with a CITES violation. It isn't like we are talking about animals in the 1000$ plus range like certain snakes and lizards or even 500$+ frogs like certain occasionally smuggled dart frogs.
I think with the demand staying relatively high (for a frog) and the supply getting low, there is more of a risk for smuggling, but definitely not like the critters you're talking about... yet. Getting the CITES paperwork is a great practice, and especially helpful if you eventually want to export offspring or what not, and hopefully you're working with people who aren't a pain about giving it to you. The problem I see is that there is a growing threat of wildlife being smuggled from Madagascar (tortoises for example), including animals in the same area. With demand greater than supply, adding in some of the pretty little hoppers while you're poaching stuff in the area may not be that hard (and significantly influencing the population of an explosive breeder in an area is as simple as collecting all the breeders gathered a a breeding spot). So the threat may not be there, but it's increasingly becoming a possibility - and one that captive breeding can actually put a stop to, or lower the risk of, if done right.

Due to the before mentioned IUCN Red List section and CITES information, the $100/frog price is probably here to stay, and may even go up.

Yes, that is possible, however demand isn't really terribly great and ironically smaller numbers being imported probably increases the chances of them being CB and established in the hobby due to the "rare" factor. All small numbers at high prices means is that the frogs will more likely go to enthusiasts who will then attempt breeding rather than to more general pet stores.
The demand actually seems to be more than the supply at the moment, or they wouldn't be $100/frog and still selling out quickly. I wouldn't say the smaller numbers is suddenly encouraging the chances of them being CB, because people have tried on and off for 10 years to breed these guys - an explosive breeder even at $35 can be a money maker. Look at the pac man frogs, Milk frogs, Red-Eyed Leaf Frog, and Clown TF for example... they can be pretty darn cheap as froglets, require a lot of work, some are even still imported in massive quantities, yet multiple people are breeding them and selling them successfully.

The difference now is that organizations are getting involved such as zoos and nonprofits like TWI - a sign to me that the general population in the hobby can't figure it out, so they are getting the specialists that breed the weird stuff involved... and if you know about the bology of these guys, they are pretty damn weird (which is why they are an EDGE species). Their tadpole was described as a new type, and that's pretty damn impressive!