At 7 yds. per quilt, not fancy ones, I figure 71 quilts , plus maybe 3/4 scrappy quilts, estimating 75 quilts.
Of course you will need to go buy more material because once you start, you won't have the exact match for the quilt you are working on.
I have loads of material, but 500 yds. I don't think so, maybe 300 yds. plus lots of scraps.