Buy the best quality you can afford. If you go to a any major big fabric store and handle the fabrics in the quilting department you will be able to tell the difference in the quality right away. Does it feel nice to touch? does it have a nice drape quality. Is there weight to it? These are good things. If you can see your hand through the fabric, put it back on the shelf. Your 7.00 to 10.00 should buy you some good quality stuff.
Buy what you like and don't limit yourself to one or two good brands. There are many.
peace