The most valuable coin I've found so far is a 1868 Greek King George Drachma that appears to be worth $500 or so. The majority of the collection is American coins. In general, those seem to be worth even less. He's got boxes full of Indian Head pennies from the late 1800s and early 1900s. There's 17,000 of them for sale on eBay right now ranging in price from 99 cents to $24,000
There are so many variances, I don't even know where to start in figuring it out, much less finding the time to examine 1000's of pennies.
Lots of American silver dollars and 1/2 dollars - no value there at all. I'm just getting started, but I wonder if eBay has devastated coin values like it has for so many other collectible items?