Just adding my opinion on Silk Naturals, for what it's worth . . .
I tried a few samples of their foundation, but it just didn't work out for me. Even with moisturizer and primer underneath, it sucked all the moisture out of my skin in a horrible way. I haven't had this experience with any other loose mineral foundation, so I'm not sure what caused the problem.
However, I LOVE their eye shadows and blushes. They do an awesome job of "duping" high-end colors. I love their "Bargain Pink" dupe of MAC's "Expensive Pink" eye shadow, for example. And I wear their dupe of NARS "orgasm" blush nearly every day.
I'm not sure what I think of their Perfecting Powder . . . it seems that a lot of their customers love it, but it doesn't really do anything for me. I ordered a full-sized jar and have been using it on and off for a couple of weeks, and it doesn't irritate my skin - but seriously, it doesn't do anything. I prefer my L'Oreal brand powder; at least my L'Oreal powder does a decent job of matting down my foundation and controlling shine-through.