As others have stated, this does not seem like a very good deal for you. A very nice demo man, even in today's market, should top out in the low $4k range (tops). A nice original funhouse in great condition could certainly be worth as much as a TMMT Pro. This funhouse, with a faded cab and an overlay, is definitely not worth as much as a TMMT Pro. Also, I agree with other points that an owner that doesn't play a machine is very unlikely to install a ColorDMD...seems fishy my friend.

I'm not saying TMMT is a good game or super popular these days, but perhaps you could get more selling it or finding a more equitable trade. I feel like you should get at least in the low $5k range for it and realize that you'd be taking a bit of a hit at that valuation but that is what happens with the less popular newer stern pros especially.