Back to the NES. Bonk's Adventure was released in 1989 in Japan and 1990 in NA for the TurboGrafx-16. It was later ported to the NES, Game Boy, the Amiga, and arcade systems. The story follows this big-headed caveboy named Bonk who fights dinosaurs and other prehistoric creatures. His mission is to rescue a Princess named Za who was kidnapped by an evil king named Drool. Great names I gotta say.

Bonk is a 2D platformer and a pretty decent one. It'll seem weird to play at first because the only way Bonk can attack is with his head. Either standing still and hitting enemies or dropping on them. It feels pretty awkward but it'll soon grow on you and it'll work just fine. One main feature of the game is meat. You can find meat in the weirdest places. Meat gives Bonk extra bonuses when he attacks. There are 3 stages of Meat Power, level one is a basic power-up giving you more damage. Level two gives you a stun when you slam your head on the ground. The third level gives you invulnerability for a short while. The game is pretty simple to understand, mainly basic platforming with some wacky features. The core gameplay isn't anything too special, you've probably seen it plenty of times before. Some of the levels are pretty neat like exploring the inside of a dinosaur.

Why so expensive?
Bonk was originally a flagship series for the TurboGrafx-16, but the TG16 was a pretty big flop going against the NES. The makers of the system decided to port their game over to the NES in 1993. It had a pretty limited release and was released 2 years after the SNES was released. Needless to say, the NES version sold pretty poorly. Just like Little Samson, it became a pretty valuable game years to come. Used copies can go for around $400-$800 used and $3000 brand new. 

I think the TG16 version of the game was re-released on the Virtual Console so if you want to try it out, that's the legal way to do it. Both versions are relatively the same except with different graphics. I played this game a long time ago on an emulator. In fact, I actually have a video of me playing the game. Vizzed.com was a magical place

Here's some gameplay of Bonk's Adventure played by 2013 me