Both of my brushes are under $100 and both are excellent.... the Omega 636 is an excellent brush for around $65 and the Semogue SOC for around $95 even nicer.
Way under $100 - either the $10 Omega 10065 boar or the $36 (the price I paid recently from the ) Semogue SOC boar Taj. Thing is, I have another half dozen or more that were under $100 that are equally as good, including a couple Kent Silvertip badgers, other Omegas, Muhle STF, and so on. In other words favorites are fungible.