The bird shop for sure!
The bird store I got Cutie from is much better than PetsMart. When I first started going there and playing with the birds, I thought it was an amazing store that did everything right. Now, I realize that they don't. My only complaint is the cage sizes for the birds. The budgies are kept in an aquarium, but they have plenty of toys and they made the top with tons of holes so there is fresh air. They have big food and water dishes too, and chirp happily whenever I'm in there. I don't recall ever seeing a sick bird.You do run the risk of getting a sick bird even if it looks healthy being caged with obvious sick bird.
Is the next pet shop you could go to (where you got Cutie from) a better store, healthy birds, clean cages, clean water, fresh food etc? I'm not one to buy any bird from pet stores anymore, but getting any kind of bird from a store that's not good means they're going to replace the one you bought with another budgie and there's a 99% chance s/he will be ill.
It's up to you, but I think if it was possible, getting a hand-raised and fed budgie from a breeder is the best option.. but that's not possible for everyone, so if it's not for you, I'd go with the store you got Cutie from and stay well away from the first one.