I often get asked, "Does it matter if I buy material at a discount store or a quilt shop?"
I quilt will both types of fabrics. I think the most important thing is that you are making something you love! If that means discount material then go for it. BUT... You get what you pay for.
Just like most things, the higher costing material is better quality. I make sure to either buy from my local quilt shop (I live in Utah and I ADORE Elaine's Quilt Shop), or a reputable online store.
The better quality will wash nicer, keep their color color better, and last longer.
I know some quilters stick to 100% cotton only for their quilts, but I have found lots of different materials that are fantastic for quilting.
So, figure out what type of quilt you want to make, who it is for, and how much you want to spend on materials. Then get out there and start a project!!