Used NES cartridge buying tip

Remember River City Ransom? That was a great game. I've had that cartridge for years.

Did you know that it was the modification of a Japanese NES/Famicom game called Downtown Nekketsu Monogatari? So a while back I decided I should buy a copy of the Japanese version just for the shits and giggles.

Fun fact: there's also a game called Downtown Nekketsu Koushinkyoku. Very similar cover art. It's...uh...not the same game though: