Intresting topic! Nice to see a poll on it as well!
I chose the $200-$299 category, but didn't read it correctly and mistook it for Pounds Sterling (GBP)
The most I have paid for a brand new, untouched, sealed game was £240 and £260 for Steel Battalion and Steel Battalion: Line Of Contact respectively (Both with controllers and sealed within their original brown shipping crates). The second highest I have paid for a single game is probably £140 for Halo III Legendary Edition during the week it was launched when you couldn't get it for less unless you had pre-ordered it.
As for other games, I can't really remember too much about prices paid (I know I should have kept a simple diary of such things), but I can recall paying roughly £75 for a sealed PAL Smash Bros for N64; Around £85 for sealed PAL Paper Mario for N64; Around £85 for sealed PAL Breath Of Fire III and same again for sealed PAL Blood Omen. Metroid II Return Of Samus for GameBoy is probably one of my more expensive pieces in my collection as well, costing about £82 if you all remember. Bioshock LE with the Big Daddy Figure for X360 I bought off eBay after release due to not pre-ordering it, and that cost me £75. Countless other rare games have been bought for between £50 and £90 over the years