Some recent serious games auctions on eBay:

Serious Games and Edutainment Applications by Minhua Ma (English) Hardcover Book

$180.43
End Date: Thursday May-17-2018 20:10:45 PDT
Buy It Now for only: $180.43
Buy It Now | Add to watch list

Serious Games, Interaction and Simulation : 6th International Conference, Rev...
$69.78
End Date: Thursday May-3-2018 21:17:54 PDT
Buy It Now for only: $69.78
Buy It Now | Add to watch list

Serious Games, Interaction, and Simulation : 5th International Conference, SG...
$68.75
End Date: Friday May-4-2018 9:42:36 PDT
Buy It Now for only: $68.75
Buy It Now | Add to watch list

Serious Games, Paperback by Abt, Clark C.
$54.04
End Date: Friday May-4-2018 1:54:05 PDT
Buy It Now for only: $54.04
Buy It Now | Add to watch list