The cabinet/Roms are valuable just due to the rarity. How many DK cabinets were made, and how many DKjr cabinets were made? Plenty. Now if this was a moon patrol that had been painted black and a cheesy bootleg marquee shoved in the slot, it would be different... but this one is well done. Now I'm not saying that it is not a conversion, but it's got sideart, marquee and funky t-molding, bezel, the whole bit. How many of these things can there be floating around?
Hell, I'd give him a good buck for it if, and I didn't ever much like DK jr.
Funny thing, there are a lot of people that I have come across in my dealings, that like/remember Crazy Kong more than the original DK. You could do that coolio cheat in CK that you couldn't in the original, and these things get their own subculture/following. Don't dismiss the clones so easily.