I was in a hobby shop about 10 years ago, and bought one of these cheap Hobby Engine cranes:
http://www.hobbyengine.com.hk/catalo...?product_id=25 I believe it cost me around $40 at the time, and I have seen them several times since for under $100. It is not very powerful, but I have had a lot of fun just messing around with it. I changed out all the 'cable' for a silver-colored string I found at a fabric store - it looks much better. The rubber-band tracks finally fell apart, but I managed to change them out for the track and drive sprockets from a 1/16 KV-1 tank. And, after all of that, the radio gave up entirely. I am trying now to figure out a way to replace it with a real one. Ha. The scale is purported to be 1/12, and that's based a lot on the size of the operator's cab. I have wondered if I can build a new body from sheet styrene that has an 'older' look to it.
But all in all; I'm glad I got it. When I finally do get tired of repairing it or trying to improve the looks; it'll just make an impressive (albeit nonworking) load.