What are some sellers for bettas on aquabid that are trusted? By that, I mean that they won't show you some great pic of a betta, but then you get a different one.
Read their feedback - just like ebay
But before you think about buying on Aquabid, think about shipping.
If you're in the US it's probably quite a good deal. If you're in Europe or UK think twice.
For my purchases it cost $5 shipping per fish - wow great... Yeah, but that's only as far as the transhipper. You then pay the transhipper a fee per fish (7Eur), a box/heatpack fee (7.50Eur) and shipping costs (between 94.20Eur and 201.26Eur depending on shipment chosen) - suddenly that lovely fish is very flippin' expensive!
Just look which transhippers are available (they will be will be on the ad on aquabid, along with an email addy), contact the transhipper first to ask how much they will charge you - if that is reasonable on top of the cost of fish, then go ahead and buy.
I would advise you not to buy any of the imported bettas on AquaBid unless money is no object and you can afford to take a loss if it comes to that. I actually had it happen to me that I spent $65 for a pair of fish and the shipping costs and it turned out to be nothing like the picture he has posted. Eventually we found out that this guy was a scammer who did business under a multitude of different names.
There are many excellent breeders in the US who are members of the IBC. Why not sift through this list and see if you can come up with something that looks interesting.