Re: Powder Foundation brush?!
SEPHORA COLLECTION PRO Flawless Airbrush #56 and Too Faced Mr. Right - The Perfect Powder Brush are great if you're looking to apply a powder. Both are light but dense enough to flawlessly apply powder to your face (or other areas if you'd like!). Both are made with synthetic bristles.
If you're by chance looking for a kit, SEPHORA COLLECTION Ready in 5 Face Brush Set is an adorable mini set of three brushes. A foundation brush, powder brush, and concealer brushes. It's great if you travel on the go and would like something to help you touch up. It also comes with a nice pouch all for $25!