I see. I have to admit I 've been stunned by how expensive driving a simple DC motor can be. An R/C ESC for a brushed 30A motor can be bought for $7.83 at hobbyking. With some creative soldering can't I make the equivalent of an H bridge using simple relays to route the current and have a cheap bidirectional DC motor controller? I must be missing something otherwise why would anyone spend so much money on the other circuits? Also, why are R/C ESCs so cheap compared to, for example, the Pololu motor controllers? I really feel like I 'm missing something blindingly obvious otherwise why would anyone buy them.