Some recent serious games auctions on eBay:

Serious Sam II (Microsoft Xbox, 2005) Complete Tested

$9.00
End Date: Thursday Oct-19-2017 9:08:44 PDT
Buy It Now for only: $9.00
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Serious Sam Next Encounter Nintendo GameCube Video Game Complete
$27.00
End Date: Tuesday Oct-17-2017 18:57:19 PDT
Buy It Now for only: $27.00
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Tri Fidget Hand Spinner Brass Triangle Metal METALIC DESK Toy EDC Focus
$6.89
End Date: Thursday Oct-5-2017 15:18:04 PDT
Buy It Now for only: $6.89
Buy It Now | Add to watch list