yes, about RM160~

Not many active Technic owners here. It depends what model you want to mod or build from scratch ?
Also, if you have the end-model or guide, normally there is a list of parts you need.
Then perhaps forumers can give their advise/suggestion.

looks like people start grab this...
i think minimum wound be a remote, a battery box, a receiver, and 2 motor (of course, u can add more part)
it will need your imagination to make it RC

not to forgot those batteries as well

First thing first, Lego RC crawls at 1-2 feet per second, do not compare to those real RC toy cars.

Here's a starting point. Most of Technic mods need to do some own test build to find the parts needed first, as they don't have full instructions.
Then only see whether to buy a box or parts.
As in the video above, it's quite informative already on the major parts and locations (at least to me).