Alternatives to retrobox for cheap computers?

Like the subject says; I like retrobox.com for the fact you can find usable computers for $100 and up (or as low as $11 for 400mhz celerons and shit); but they want $30 *Per Item* for shipping. I was wondering if anyone has any suggestions for other cheap sites that you can buy used computers at (NOT ebay)?

Ask around local schools and colleges for old stuff they're getting rid of. Many take the "if you can haul it off, it's yours" attitude.