Listing and selling are 2 distinctly different animals. Keep in mind however, that pre 4 tractors with substantial power and capabilities are commanding very high prices and are climbing as the 'for sale units' decrease.
Not made anymore so what there is, is what there is.
Good example is my open station fully restored M9000. My dealer offered me 32 grand for it last fall. New it listed for 35. I'm sure he could have sold it for list price or he would not have offered me what he did for it.
Bought it used in good condition for 16 (not from him) and put an additional 6 in it and it's not for sale, least not now. Same deal with my other M9000 but it's a cab unit all optioned out. I bet I could ask list on TH and get it no problem. Same with the OS if I was inclined. I'm not.
As pre 4 units become more and more hard to get, mine become more and more of an investment. Fine with me. same deal with my 1997 OBS Ford 7.3 pickup truck. It's in pristine condition. Was offered 26 for it last year, cash. Not for sale either. Paid 31 new in 97.