Why do you want to value PAL games with the NTSC prices?  Or are the games listed in a particular lot actually NTSC instead of PAL?

X-men cards would be pretty sweet.  Are they based off the comic or the Saturday morning cartoon?

I've removed some of these that seem to be repros based on the prices.  Most of the sales are fairly old so I can't see what the listing actually said.  I'll keep monitoring this to try and see if I can find a pattern and remove these before they get into our system.

Thanks for the feedback.  I've removed some junk Vampire Kiss sales and the value has been recalculated.

For Aero Acrobat 2, this looks to be legitimate copy:

https://www.ebay.co.uk/itm/Aero-The-Acrobat-2-SNES-PAL-SNSP-AE2P-FAH-/124307471450

Can you tell me if it is otherwise?  And how you can tell.

I'll look into the other games too and remove any repros we can.

We do not want repros on the site and actively try to remove those.  Are there certain keywords that listings say in the description that indicate they are a reproduction?  We toss anything that says "reproduction" but we might be missing some other keywords that tell us to toss those.

I've added this now.

https://www.pricecharting.com/game/pal-super-nintendo/cool-world

I'm flattered that you think we are that big a portion of the video game marketplace.  Most sales and purchases for games happen without ever checking PriceCharting.  We do not change the prices of the market, we report on the prices.  

I'm very confident that the market price changed because people from USA could decided to import a region free game from Europe instead of paying crazy high prices for NTSC game.  So there was less demand for the NTSC game.

We will never really know the cause and effect unfortunately.

Any listings that do say PAL or UK version or similar things in the title are moved to the correct region.  Same with NTSC ones.  We do the same with games sold in UK or Europe even if they don't say specifically what region the game is for.  Unfortunately most of these sales are from US sellers and they aren't specifying the region so we assume it is NTSC because we can't differentiate based on photos at this point.

I've moved a bunch of these sales over manually but it looks like the NTSC game has gone down in value too.  There are lots of NTSC sales for lower than price was a few weeks ago.  Now that people have more options to buy this game, it is natural for the price to come down.

If you can give me links to these items online with photos then I can add them.  Hardware can be tricky to make sure it is accurate because the names aren't always standard.

This is already a feature.  If you click "show chart" on any individual game page.

For example:

https://www.pricecharting.com/game/gamecube/007-agent-under-fire

I'm going to change that link to be more clear about what it does and it will say "Show Historic Prices" within about 24 hours.