The website 130 Point (https://130point.com) is an incredible resource if you’re trying to price cards for sale or trade. They show the actual selling price for eBay sales, including accepted best offers, so you can get a true gauge on the current market of a specific card or box/pack of cards. You don’t end up with inflated numbers when things are listed with a high Buy-It-Now (BIN) value. You can also check sales from other marketplaces, and items that are currently for sale.
The site also has pretty comprehensive set listings, so you can view all cards for a player, a checklist for a certain set or the number of autos available. Unfortunately, it seems like this feature has been neglected and most of the data is out-dated.
The name 130 Point is a reference to a card thickness often used for memorabilia inserts.