There is not enough time to look up the value of items you see from the door then make an educated bid on the locker. Thats a body of knowledge you just have to keep in the ole memory banks. They are great for flea markets and yard sales. Download the Bar Code Scanner App, it scans product bar codes and UPC numbers and then you can find the retail price and ebay price of the item pretty quickly.
Actually one of the reasons I have got more into storage auctions as opposed to yard sales and flea markets, is because of technology like the internet, ebay, smart phones, the average seller has become a lot more savvy at pricing thier merchandise. I stopped going to yard sales because soo much of what I found was priced right at the Ebay ask price. Guess what people say when you offer a lower price? "Thats what it's going for on Ebay!" I say, "No, thats what somebody hopes to get for it on Ebay!" Don't get me wrong, there are still a lot of great deals at yard sales and flea markets for the serious hunter, but I just got tired of all the driving and gas bills.