I encourage you to check actual reviews before ordering from a couple of these places. Especially if they're importing shrimp in bulk, brag about keeping massive shrimp tanks or do things like offer multi-color "packs" of Neo shrimp. Those are generally sellers focused solely on a bottom line and don't put a lot of effort into making sure the shrimp you receive are in any way healthy.
Good advice in some of these responses, though. Particularly about buying from the For Sale section. Buying from other members will often allow you to see how they keep their shrimp, how long they've been in the hobby and review whether or not their shipping practices are good. Most will have tank journals with tons of photos and details that will allow you to see what they're up to. You'll also likely end up spending less money and get healthier shrimp.