Well, he was an idiot to sell it for that little. Home bought machines are nearly unheard of for big reds. It's more difficult to find them than US Metal Slug 1 or Neo TurfMaster carts. Imagine buying a $2K cab straight from SNK and then selling it for that low of an amount without doing your research?
You certainly got a good deal but that doesn't mean that's the true value of a cab like that. Every single time you see a Neo cab for sale, their play counts are 20K+, some over 50 and 100K. If I was to see another sub-1K count original home-owned Big Red, I would not hesitate to pay $1K+ for it!
Sincerely,
Mikhail