I haven't paid a fortune for a brush yet, my weapon of choice to start me off is a Wilkinson sword natural fibre brush from Tesco (£3.50). That lost hairs really badly for the 1st month but then settled down although it looks a bit messy when dry.It does the job it's made for (actually quite well) so I'm happy with it for now!
Don't own a Parker, but I read a lot of negative comments about them.
Look at whipped dog, 2 badger brushes for under $20 and the black badger has a good backbone.
Semogue 620! I find very smooth and soft, yet still scrubby with just the right amount of backbone!