Barry,
I've seen seven (7) of the Stratosphere $4 chips sold on Ebay (I may have missed an auction or two).
The autions I have watched ended with the following winning bids:
$18.50
$42.50 (for a set of two different molds)
$19.99
$18.38
$19.99
$17.35
Total
$136.31
Average
$19.47 each