High price tends to be due to a few things. Rarity factors in. So does usefullness to an extent why 4000s get a good price, 1200s. Why a 2000 tends to do better than a 500. But a 1000 gets a better price than a 500 though the 500 is technically better and they are similar as far as expandability (500 is actually a bit more expandable).
Though later on they were remade into Mac XLs, actual Lisa machines with the 5.25" drives are a bit rare. Lisa didnt sell well, which is why there were Lisa's to be remade into MacXLs to try to recoup costs. Is it worth $25,000? Thats just a "Buy It Now" someone decided to set for it. Since it hasnt sold its not yet worth that. You only find out worth from when it sells. I did see a C65 sell for $20,000 (at least I assume it was an actual sale since it was an auction and it ended on ebay at that price but you never know if the winner actually completed the transaction). Usually a BIN like this is someone hopeing to grab someone who doesnt really know value and make a mint on something that doesnt take that much storage space. So they can tend to hold on to it for a while in wait for the sucker.
Lisa does command a decent price due to rarity from being a poor performer therefore rare. So does the Apple III, Atari 1200XL, and Amiga 600.
Amusing anecdote is everyone says Jobs went from Xerox and took what he saw there and came up with the Mac...huge success...amazing foresight, but in truth he took what he saw at Xerox and came up with Lisa first.
