Where do you find motors like on the duel 20d setup ??
BangGood has a selection of motors as well as Amazon. Research what RPM you are after, this will pay off in the long run. Most guys are running 150-200 RPM but you may opt for 300 or 100 depending on torque requirements and speed
where to find D20 motors? Ebay. ~150rpm, but they are not so powerful like expected.