The LB powertrain will handle the brushless power, no problem. It's the body and body mounts you'll need to be careful about. But then again that's not a problem either with good driving. Or just set the end point of the throttle lower so that you give yourself a speed handicap there.
The real reason you should get a BL system is that unlike brushed motors, the motors have no brushes that you'll need to replace after a every few runs. They are more durable and require far less maintenance.
But if you need to stick with brushed, there are plenty of cheap ones for about 20 USD or less. I have a good Venom brand in mine. Although, 1 reason I wouldn't recommend it is that its on/off switch is tethered very close to the ESC. It's not like the Tamiya ESCs that have long strong wires and large switches that you can mount on the chassis.
Shop around. There are a lot of cheap brushed ESCs. Better yet, there are many cheap brushless ESCs. Makes no sense anymore to stick with brushed if you're spending money.