Reversing camera

Has anyone done a good cheap reversing camera in their 90/110?
I am doing a big rebuild and most money is already set aside to finish it but I would like to do a reversing camera during rebuild but funds are tight, any advice or recommendations?

You don't have to spend a lot of money. I used a 30 quid camera from maplin, made up a bracket to fit between the legs of the tow bar to locate it, then connected it into the reversing light circuit. The camera output cable then went along a chassis leg up through the engine bay to the back of the dash. I had a flip screen sat nav/dvd player/radio to use as a screen, but there are loads of screens on eBay for not much money.