I agree -- I freelance make-up and have not, in a lot of searching, found a drugstore foundation I would use on my clients.
"High-end" (department store/beauty store) foundations tend to be longer-lasting and more intensely pigments (you use less product) than drugstore items. Same is true with blush, eyeshadow, etc. So that $24 blush will last you as long as that $6 one because of pigmentation and stay issues in drugstore items. There's also usually a difference in product weight (for example, a NARS blush is at least two to three times as large as a Covergirl one, so we're already talking that before we even take pigmentation in to account).
That said, I've heard good things about physicians' formula and revlon Photoready (I was impressed with neither).
I've also noticed an improvement in drugstore eyeshadows, so over time I wouldn't be surprised to see these products continue to get closer to department-store quality. But for this make-up artist? Not yet