I have completed updating my 2020 Ebay sales database. You'll find the current actual price (including shipping) of many vintage and rare RPGs, as well as the results of Ebay sales. If you would like to see any older games in future that is not currently included in the Excel file. Leave a note here, and I'll track it and report on its' value in the future. Middle column is shipping costs, by the way.
2020 Vintage RPG Values (Based on actual Sales Data)
https://drive.google.com/file/d/1vnQFVm9_8Dc2RwPASXFUC8q0ir1DNLEH/view?usp=sharing