Well,
this 7s/200A is close for a really cheap price. I was really eyeing this one, but not sure how well it works for cars or if it has reverse. 7s=26v.
If you want 30v, I assume you are looking at an 8s setup? That's starting to get into the "HV" realm and those aren't really cheap. There are a few aircraft ones around for cheap, but you generally have the slow ramp-up in throttle which some don't like, the burst current isn't all that great, and most don't have reverse (although you could do some type of mechanical servo-actuated reverse system). And some air ESCs won't work with a pistol grip radio without a pistix adaptor.