I don't have any experience ordering from AB, but I've looked around the site and considered buying a fish from there before. I don't know what country you live in, but you might want to look at fish bred in/near your own country because you don't have to deal with the hassle/cost of transshippers that way. Shipping a betta from Asia to the U.S. is really expensive, and the longer the fish is in transit, the likelier it is for him/her to get hurt or stressed. I'm not saying it's bad or wrong to buy a fish from overseas, just that, for your first experience with AB, it will be easier/cheaper if you don't have to go through transshipping.
Some people have ordered fish from breeders on AB, then realized that the fish they recieved was not the one they bid on, so do look at the breeder's feedback from previous buyers. Also make sure anyone you buy from has a DOA policy, and that it is clearly outlined. You don't want to have to pay $60 dollars for a dead fish.