Thank you all for the support. The girls at the pet store said a man had incubated them and brought them in at 1 day old. She said she noticed a few days later that some of their toes "looked dead" and some were even bloody, and called him but niether he nor she knew what the problem was (and obviously didn't really care either to let it go on). Apparently she had sold a couple to a woman who was going to have a vet look at them and then call her back, but she never heard back from her.
I've heard of bumblefoot in chickens, but that is pretty uncommon and usually starts with a small injury or splinter. I don't think that would apply seeing as so many were afflicted. The only thing I can think of is that it was caused by the bedding they were in (it was pelleted and looked like hamster food). Perhaps it had a chemical in it or wasn't kept clean (it was pretty moist) causing the infections. I don't know...but I will keep you all posted!