Your comments

Can you please link me to the exact Super Mario game you are referring to?  I'll look into removing any sales that are listed by mistake.  

Heritage Auction is a source just like eBay though.  We consider them in our pricing calculations.  Heritage is much more focused on the high end market though so generally their sales only impact the Graded prices.

Thanks for that suggestion. So you'd rather the "add another copy" feature would just increase the quantity available for that item instead?  

If you click on an item in your collection already and then click "Edit", you can change the quantity there.  That might be a work around until we implement the change you requested.

Thanks for this bug report.  I'm looking into what is happening and hopefully I can fix it soon.

Can you explain this feature idea a bit more?  Can you give me a url on the site where this would be an option?

Our site does calculate a market price for video games.  We calculate it based on actual sales data.  A buyer and seller agree on that price and a transaction happens.  Yes prices have been going up, but that doesn't mean that isn't the market price.  If a buyer and seller agree that is the price then that is what they agreed.  

We do not include listing prices (just the price that someone wants for the item) because a buyer hasn't agreed to pay that yet.

Depends on how many people ask for it.  If only two people want it, then we probably can't justify the development to add that to the site.  Not worth the time or cost compared to other features that users want.  But if this turns out to be popular than we can add it sooner and it will happen.  Sorry I can't give a definitive answer.  That is why we have the request tool so I can prioritize these things.

Can you give me some examples of these figures?  Links to them so I can lookup more info.