For fun I check eBay every year or so. I've seen them on there anything from $50 sometimes, right up to $3600 I think was the highest I've ever seen. Average is around the $1000 usually. I think it depends on whether it is first edition or not, or signed by Brian at an airshow etc.

Hang on to your two - could be a better retirement plan than crypto currency! :D

EDIT: Here is one current listing ~USD$640 - https://www.ebay.com.au/itm/Sled-Driver-Flying-the-Worlds-Fa...