I actually use the brushes from Bare Minerals because I spent so much money buying their kit, but then couldn't wear the make up! Their brushes are very nice though, although have not held up well after a few months of use (the handle comes away from the foundation brush). I know you can buy good brushes from Sephora but probably not cheap. I have bought a couple of brushes from Everyday Minerals recently (their old brushes were not so good, but they have a great range now) and have been really pleased - try the 'premium' range. I'm not sure, but I think you're supposed to use brushes designed for mineral make-up, and obviously the ones from Everyday Minerals are.
I would recommend a concealer brush and a foundation brush to start with, or if you prefer heavier coverage, some sort of kabuki brush to apply the foundation, then a foundation/powder brush if you use one of the finishing powders. These should only be used for the concealer/foundation/finishing powder IMO - use a separate brush for blush.
Good luck - I hope it works for you - Everyday Minerals are my lifesaver - wouldn't dream of going out without them! I'm already worrying about the trip to the dermatologist next month as I will have to go make-up-less - gulp! Oh and by the way, people never guess I'm wearing make-up, its that natural looking, the redness just vanishes behind the multi-tasking concealer.