There is nothing wrong with buying fabrics at Walmart or Joann's for that matter. If the fabric is nice and the price is good, so be it!! If I am going to pay $10 a yard for fabric though, I am going to go to my LQS where there will be a bigger selection of $10/yd fabrics.
I have made some very pretty items from Walmart fabric that have withstood the test of time. As quilters, isn't that our main creed: To be thrifty and frugal????