The fabric I bought from Connecting threads, the frost line, when it was on sale(because I'm cheap and well I saw it when it was on sale) was really decent fabric. It's silky smooth and heavy fabric. I haven't noticed any differance and in fact it may be thicker then the scraps I got from the Bernina store.
Though to be honest, I haven't noticed a whole heck of a lot of difference in quilt shop fabric vs Joanns(gasp) or Hancocks. But I will have to say Connecting threads has some of the best quality that I've bought.
The reason they are so cheap if you go and read them on their site, is that they cut out the middleman. They order directly from the mills instead of a another person who delivers it to the quilt shop.