Is your craft set up with 2 motors originally?? If you are prepared to
do some mods, you could get away with one brushless motor, something
like a Feigao 10XL on 4S could be a goer. You can pick those up for
around 70USD and match it with a 100amp mystery esc for around 50USD.
Alternatively if you want to stay with brushed motors, 19turn should be
ok if you run 2 of them, you can buy brushed esc's that do 2 motors
however they are getting hard to come by and they usually cost quite a
few bucks. I got one a couple of years ago, it is a Kyosho Perfex with
water cooling and it was around 200AUD. You could also look for an esc
for a Traxxas Villain EX, they are a duel esc as well and also come
with water cooling.
What kind of budget do you have and how fast do you want it to go is
the big question.

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deestingray