I'm not in the same country as you so I don't know of specific websites, but I'll list some ideas off the top of my head:
General online forums for people living in your area.
Fish-keeping forums.
Amphibian forums and websites.
The selling section of this forum (if you haven't already listed there).
Try Googling axolotls or newts in your area and see what comes up. See where people are selling those and list your frogs there. Obviously also try Googling ACFs in your area. I expect that you'll get less results though if it's anything like here.
General pet selling websites (I don't know of specifics in your country).
Facebook selling pages.
If you know of any fish/reptile shops that look after their animals properly, ask if they're interested in selling any of them from their shop. They might be more interested when they're semi-adult frogs though.
Contact zoos, sealife centres and public aquariums to see if they're interested in any.

That's all I can think of right now.