Who are you planning on buying from??? I frequent aquabid quite a bit, and there are some sellers that are fabulous, and others that should be avoided like the plague. If I don't know about the seller personally, I could probably find someone who has purchased from them, or find someone with a good reputation to sell you a similar fish.
Shipping fish, and my only experience is with bettas, works quite well. If you're ordering from overseas, MAKE SURE THEY USE A TRANSSHIPPER, or else you're risking major fines from game, fish and parks. If they're shipping within the US, use overnight shipping only, and make sure the seller knows how to pack the fish and ship fish, especially in the winter. The more experience they have, the better.