I paid $79.99 to get "Jurassic Park" for the SNES for my little brother for Christmas. Yes, I felt ripped off.
I too have seen prices for SNES games in the $80 range.
DaveMMR is correct though. Most games usually aren't over $55ish. $50 is considered the sweet spot for most games with $20 being the budget range and anything over $80 starts into the high end/collector stuff. I do, however, have some store receipts for Atari XEGS games and those were rarely over $40.
For a long time, the only places I've seen games in the $80 were the local stores in my town. My friend shelled out nearly $90 ($80 + hold deposit) for Castlevania(sp?) and spent the better part of six weeks paying it off with his allowance. Just as he managed to pay it off, my father drove us to Reno and I bought Super R-Type for a measly $30-ish, where he saw his Castlevania selling for half of what he just paid.

The stores that ripped us off were those that knew they had a "captive" buyer. Little kids with no real means of transportation to the larger stores in the city and, more importantly, not enough patience for that transportation to come around. This was all before most of us had access to the Tubes so it wasn't like we could check Amazon and compare prices. Now, not a single store in my old town sells video games (barring the rental store and their used game collection) because the kids are a little bit more savvy.
The link DaveMMR pointed out does point out that it does depend on the specific game title. What was that game with the MONSTER full blown dashboard? Battletech or something? That cost a pretty penny.