Well I went to Sephora today just to pick up some brush cleaner. I got this awesome makeup brush when I bought an I.D Mineral makeup set there, but it didn't come with a brush case, (mmm maybe I should let them know that would be helpful.)
I usually just throw my brush in my purse with the rest of my makeup, and I try to make sure I seperate my keys and cash from my makeup because yuck, so many germs, but without a case for my brush it is hard to keep it germ free. So I had to get a brush cleaner.
Buying another brush and a brush set is more to carry and also sometimes it can range up to $20--$50 bucks for the right makeup brush, so replacing them is not cheap, and carrying a brush kit is a heavy pain in the butt.
I think I will clean my brush instead each day. My face/skin is pretty tough and I haven't had many blemishes over using the same brush, although I would be careful to clean your brushes, because your house keys and your makeup brush should not touch and if they do, that is nasty for your face and can cause break outs.
The brush cleaner at Sephora is only $6.50 and worth it!