Nope, they go down into the hundreds. I don't think I've seen <100 but I have seen <200KV. Big ol' props are mounted directly to them so it kinda makes sense.
That's an outrunner motor for airplanes. You can't even put a pinion on that.
You could get a Spektrum 150A system from a 6s Arrma (hobbywing makes them) for 200ish bucks at Jenny's RC (they take apart new RCs for parts, so everything's new but no warranty).
IMHO a 4s system is more than...