When I started watercolour paintings, the brushes I bought are a mix of synthetic and hair, decent brushes without spending great wads of money for sable. I've also tried sable brushes and they are really worth the money but so expensive. I didn't buy them right off the bat because, knowing me, I didn't know if I was going to stick with painting. Then Opus put their Winsor & Newton sable brushes on sale - 25% off.
Be it knitting or painting, use the best tools and materials you can. It really does make a difference. So true.