$10,000 to $25,000
Depends on:
1- how bad a buyer wants THAT ONE!
2- how desperate the seller is to have it gone NOW.
I have personally bought and sold them in the low and mid $30's.
I have seen documented sales here on the forum in the low teens, and every single number in between those two extremes.
Good luck!
Buy the best that fits within your budget. Paying up now for one that has had all of the proper maintenance already done will almost always end up being less expensive in the long run, than buying a neglected one for cheap and having to do tons of work to it.
Stretch on the the buy will make you much happier as you will likely have less problems!

Marty