Some recent serious games auctions on eBay:

Serious Sam Collection + Case (Microsoft Xbox 360, 2013) 4 Games in 1 - Free S

$12.95
End Date: Sunday Nov-19-2017 19:04:32 PST
Buy It Now for only: $12.95
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Serious Sam: The Next Encounter (Nintendo GameCube, 2004)
$11.00
End Date: Saturday Nov-11-2017 16:11:07 PST
Buy It Now for only: $11.00
Buy It Now | Add to watch list