I buy from JAF mainly, when I can make a trip to the US.
I also buy from Fabricland when they have their 40% off sale and I always buy something from our LQS's when I am nearby.
I'm really torn because, while I would love to support our local stores more, I can't afford to pay $26.00 a metre for batiks and $18.00 a metre (plus tax) for cottons here. So, I feel guilty that I buy in the States, but the option is not to buy what I want/need for my hobby.
As to what I use in each quilt, I use whatever the quilt calls for. In most of my quilts I have a mix of both really "nice" fabric and maybe some lower end stuff that I liked the look of.
Watson