the kai chassis is far more expensive than 130$
i think you should buy the new 1-way too
a comm lathe is used to "cut" the commutator on the motor's armature
after a few packs the comm starts to get "dirty" (dont know how to describe in english
) so u need to cut it with a comm lathe, which is pretty expensive $70...so it is why u can buy it with some of you friends .
if you are afraid of pneumonia go isolate urself in one of those tiny island around HK
take ur sunglasses and an off-road r/c car!