The quality of the fabric depends on the goods that it is printed on and generally, the printed goods done for the discount stores is of a cheaper base fabric than that for the quilt shops..
Now, that being said.. you will find good fabric in a discount store.. I recently purchased 200 thread count solids at Hancocks and I cant even find a thread count that high in a quilt shop..
So, what I do is look at all of the sources and buy the best where I find it.
I have a small online fabric shop and I do the same when selecting fabrics for my store.. I must feel the fabric before purchase..I have had some nice fabric and some not so nice straight from the manufacturer.
If you purchase a nice fabric for you swap, who will know where you got it?