Things have happened. (I have gotten hold of 'Teenage Mutant Ninja Turtles' for the trusty NES though.)
Well, as for selling the 'Metal Slug' sheets, I'd rather swap them. If I wanted cash, they'd be on E-Bay. This is a collector's forum really, so I'd be more interested in swapping my spares for other people's spares.
(I'm easily amused and easy to trade with) Many things that you may trivialise, I am actually chasing. Two fine examples are 'Rambo - First Blood Part II' for the SMS, and 'Double Dragon' for the NES and MD. I will swap an unopened, pristine, very collectable NES 'Batman' or 'The Punisher' for any of these carts.
I'm not interested in profit. I'm interested in videogames.