I'd post an ad in the classifieds. That is probably your best bet, just post a Want to Buy ad ther and people may respond. Problem is, I believe export was banned and the only way to get them is through captive breeding efforts, which can be pretty scarce IME.
Ward Science in New York sells adults. I know several people here breed them. They have specific requirements but are easy to provide and easy to breed.
Buying captive raised is great option but you will likely get 1-2" babies. I think they are easier after they reach 4". Classified here is a great starting place. I will have some in September but you probably NEED them sooner.