The crickets I raise usually spend their entire life cycle in the bin I put their eggs in after collecting them. Even though I only leave that container of eggs in there for three or four days after they start hatching, there will always be some in there that are still very tiny. I have no idea why there is so much size variance that can't be accounted for by the three or four days the eggs were allowed to hatch.

From what I've gleaned from the sites of cricket farms it seems that they really go by how many weeks old they are and then equate that to a size, that may or may not be what the crickets really are. When I have to buy them, I usually order them smaller than my desired feeding size. Then in less than a week, they'll be feeder size.... usually. Cool temps really slow their growth.... sometimes. Purchased crickets need a good day or two to get gutloaded as you can't be certain how well your purveyor fed them.

In your case, with purchased crickets molting so readily after purchase, then they definitely will be bigger than what was purchased.

If your Pet's At Home can provide you with small enough crickets that you can feed till they get big enough for feeders, that still may be the most economical..... not that raising them is costly. I spend almost nothing now that I have the bins. Kitchen scraps are what they are fed, and a little bit of dry cat food.

Asking around for others that might need crickets might need crickets could turn into a nice social thing, or it could become a business to earn extra money...... You might could become the supplier for Pet's At Home.