A couple weeks ago there was a discussion about train camera systems. I suggested a cheap alternative by getting a wireless camera on ebay or from Hong Kong and mounting it in an empty car.
I thought I’d get a couple when I went to China next time. Well wouldn’t you know someone has beat me to it.
Check out this link
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3172422124&category=481