I've just bought two beautiful females on aquabid and they were healthy as could be upon arrival! Just make sure you either get EMS overnight shipping, or if you opt for Express Mail, CALL YOUR POST OFFICE and ask them to hold the package for you so you can come pick it up from there - if you don't, the fish will be stuck in that box in a mail truck with no A/C for who knows how many hours, and that's the most dangerous aspect of mailing fish. I also prefer to buy from within the US because the idea of a betta having to be shipped over from Thailand would make me feel guilty.
Also, you can contact breeders on aquabid directly and ask if they have any females that would do well in a sorority. They tend to know a lot more about their fish than pet stores and can purposely send girls with more docile personalities. Often they will sell to you directly so you don't even have to worry about other bidders on an auction. Of course, you'll need to quarantine for 3 weeks and the fish may be stressed and aggressive at first just because of the stress of the journey. And there's no sure way to predict if a female will do well in a sorority. Some fish just aren't meant to live with others.
So far, all of the sellers I've worked with both on aquabid and ebay have been super helpful and knowledgeable, and able to help me pick out the right fish for my situation :) One seller who is particularly helpful is blackwaterbetta on ebay (she also has a Facebook page where she posts about her fish for sale and updates on her fry).
Last edited by babystarz; 08-08-2012 at 02:06 PM.