I had to sell PAL SNES collection (after painful deliberation) a few years back after being made redundant vs unable to find work.
I had PAL CIB copies of Ninja Warriors, Mega Man 7, Final Fight 2 & 3 and Super Turrican 2 to name a few. I did research on them at the time to see how much they were worth and turned up nothing. Literally. Presumably due to their rarity. I'd searched for them months before selling for pricing ideas, ballpark figures etc and found zero.
In the end I put them all up, individually, at around £40 - £60 a piece (starting bids) on eBay, only for them to finish at prices I'd not comprehended possible for SNES games. Ninja Warriors alone ended at around the £300 mark. As did Mega Man 7.
SNES collecting has been nuts for sometime now. Probably just retro Nintendo collecting in general tbh. Seems it has a bigger pull/attraction > SEGA which is worth much less by comparison...