What happens when you try to use the existing UPC scanner?  Can you share a screenshot?

We have a web app version.

https://www.pricecharting.com/page/app

That is a good idea.  This capability is already available for the Lot Automator.

https://www.pricecharting.com/lot-value-automater

If that tool works for your exact use case, then you can store the values for 30 days.  

Users can click "report" link next to any sale on the site and report this to admin and contributing users.  Contributors can use a page like this:

https://www.pricecharting.com/ebay/questionable-sales

And review reported sales too.

We plan to add something like this in the near future.