I'm sorry about your bettas too.
I bought my girls from Petsmart this past weekend - over 2 shopping trips on Saturday - I picked up 7. and 5 of them are going strong. - I've got the 5 spread out in 3 tanks - the largest one is solo. - And, I'm trying to get my large 20 gallon tank prepared so that I can set up a sisterhood for them all, with lots of plants for hiding.
My limited experience with them is that they're really complete loves. They don't do what I want them to. I bought them betta pellets and none of them will eat them - so I keep feeding them the dried worms and brine shrimp - and they really go for that stuff...
I need to research though if they're not eating the 'betta' food is ok or not. ARe they getting proper nutrition by only eating the dried shrimp & blood worms?
Anyway - I would recommend that you don't give up on bettas. There are some healthy ones out there that need a loving home, still - find them and save them, please, you know they'll thank you for it.
Your Petsmart sounds horrible... such is the case that Bettas always seem to find their way into the tiniest, unhealthiest positions in stores. No animal (& fish) deserve such cruelty.