If the monitor works and there are a few decent carts, then I think it is a heck of a deal, even if you have to replace the board completely.
I bought my NeoGeo because the price was right (and I was afraid of auctions at the time) and now it gets more play than anything else (it's almost annoying because my son wants me to change carts at least once a day).
Now, if I were you, I might change the button configuration to match original Neo-geo layout and might remount the board (if needed) for easy cart changing, but that's minor stuff.
Cheers.