Your comments
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.
I could be possible to add a variant like [English] or something for the PAL game. We don't track AU different than UK though and it looks like the Italian version might be more valuable too. I'll have to wait to see how popular this request is before working on it though because we've never done [English] as variant and that could cause some unforseen consequences with other listings because it is a pretty common word.
Closing. Added this here with that sale
We do not have a feature to import the prices paid. I'll see how popular this feature is before we try to work on it.
If they are region free (no rating on them) you can add those now to NTSC.
If they are asian rated games, then I'll have to wait and see how popular this is before deciding on implementation.
Customer support service by UserEcho
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.