Cheap ones: Sonia Kashuk about $10 for powder and blush brush. $4 for eye brushes, I have powder and blush brushes, not bad for the price.
Or you can buy a brush set from Sephora, about $36 for 5 brushes plus a brush roll. I don't have it, but Makeupalley.com recommend it.
I also own two Trish McEvoy brush and two Bobbi Brown brushes. They are better made than Sonia Kashuk brushes, softer and more densely packed, but of course, much expensive! So, if you don't want to spend tons of money for brushes they may not be a good option.