Your comments
You can already add multiples of the same item.
You can add a second copy to your collection and set the grade on each one independently.
On the website, you would click "+Another" option after hovering over the "in collection" button.

Sorry for this bug. Are you still experiencing this problem? If so, can you let me know the url where you are clicking wishlist and it isn't working? Or screenshot would work too.
Closing as duplicate. I moved the comment over to the existing issue.
https://pricecharting.userecho.com/communities/1/topics/2235-add-shoes-sneakers
As someone who collects many things, Pricecharting has been great for managing my inventory as well as getting an idea on value. While knowing what something is worth is absolutely important, the biggest benefit Pricecharting provides is an excellent way for me to know what I have, manage it and also receive emails on items I am interested in.
With just the collection curating/tracking benefits in mind, if Pricecharting was able to incorporate sneakers into the database, it could become a single source for almost everything collectible. There are NO other products or apps currently available that provide the flexibility or ease of use that Pricecharting does, and taking into account the scale of the Sneaker collecting market, there is a huge potential upside to bring those users into the fold.
With Pricecharting's ability to plug into e-Bay sales already the added benefit of having value is also there, but just the ability to manage, maintain and know what my sneaker collection is at a glance, would be a huge win for that collector community. Just my two cents....
Yes, you can do that.
The url would be:
https://www.pricecharting.com/game/4637125
That will redirect user to the correct item on our site.
Can you give me an example url that is the final destination you want for the user?
What are you wanting us to do with this list? We should have all of those items in the database already.
Customer support service by UserEcho
Physical protection like sleeves? Or some other kind of protection like insurance