If you're getting them with the intention of hatching them, make sure that if you buy them decapsulated, that they are meant for hatching. I know of at least one product that was made of decapsulated eggs, but they weren't for hatching, just for feeding as they are.
They aren't hard to decap yourself. http://saltlakebrineshrimp.com/decapsulating-brine-shrimp/">http://saltlakebrineshrimp.com/decapsulating-brine-shrimp/</a>
Jenn