The electronize controllers you describe are the ready built 15 amp ones for £34 each. I cant say if they are right for you without knowing what drill motors you are using (and probably not even then). I think they would probably be OK - perhaps someone who has used them in a drill motor powered bot will read this and comment. I use the 30 amp versions of these with external relays (£46 each) and they are very good. Im currently using them to run 24 volt drill motors and they work well.