based on offers I had thrown at me immediately, a 962, 939, or pmm would sell to someone at 15-20k- I understand that that is insane, but thats what people will offer. 800 series somewhere from 7000-12000 depending on which and if its a production amp or a modded marshall. Beyond that I have no idea. I got mine for 9k, which while a lot was fair imo. I do think its the best amp ive played, but I also dont think any amp is really worth that much, and the crazy offers I got for mine reflect rarity rather than worth. Personally i wouldnt recommend anyone throwing more than 5k at something that is not a 800 series or higher, or a recently modded one. All subjective, but based on my own offers and prices I know stuff has sold at.