I have noticed as I look at penny values some web sites give extreamly high values then you can go to Ebay and see the same coins for near nothing, where is the most accurate site for determining coin values?
Price guides are just that, a guide. The best way to tell what something is worth is to check auctions that have ended. There are multiple auction houses and eBay that you can check. Whenever I go to sell a coin I don't look at the price guide at all. I always look at completed auctions and set my price accordingly.