tfishell: I have a computer case, MSI mobo, Athlon 64 3400, and various other parts from a ~2004 machine I'm interested in trying to get some money from, but obviously for cheap. Has anybody here had success doing this?
Probably not worth it, unless any of the parts are rare and have special value for collectors or tech historians. But it doesn't sound that way. Athlon64 with 3.4 GHz on an MSI mobo was an extremely common combo 10 years ago - good value for low cost.
You can enter some of the parts in an ebay search, and search explicitly for past auctions, to get a feeling for the price at which these items sell (if they sell at all). You may need to be logged into an ebay account to perform this specific type of search.
Selling computer parts that are 2-4 years old is often viable, but not for common stuff from 10 years ago. The only item of that age that I ever found worth selling was a specific Cherry keyboard with programmable keys. I bought that in 1991 for 80 German Mark, and auctioned it off to a keyboard driver programmer ten years later for the same price.