I agree with Marlene: always buy inexpensive brushes, though sometimes fine glazing techniques require certain soft hair brushes that may be costly. Just be careful. For me, I have found no difference in brushes for acrylics and oils--the old concept that synthetics are not good for oils is more of an advertising ploy than reality. I use all types---even little kids' craft brushes--if they fail, I discard them. Of course, expensive brushes will do, too, but are generally uncessary. For what it's worth, in my 40+ years of painting, I can count on one hand how many brushes I've had to throw away--somehow their life remains endless.
