if you're loking for good under $120 USD you'll probably be looking for used esc's like an LRP QC2 or QC3. I run a QC2 in my B4 with Reedy Quad-Mags and it's a powerful yet smooth combo. You might find a brand new tekin G-11 still available in your price range, try stormerhobbies.com
You might want to consider spending a little more and getting a Tekin RS or RS Pro that will run anything brushed, brushless (sensored or non) they go for about 200USD (£130) but you'll be set for anything on the market now and in the near future with that.
GV2 Pro, XXX4G+, Blitz SCT, CRC GenXL