I'm terrible - I used to buy at least 3 yards/meters, but I do have quite a good stash now; and am also buying better quality fabrics now so they cost more ... am more often now picking up 2 yards/meters. Unless I really love it, then will get 3 - 5.
Can't even get single fat quarters - seem to have to pick up two of each.
I try to limit myself to only the fabrics that make me drool - but gosh, there are soooo many :)