around $10,000 with those hrs and condition, 25 feet shouldn't be any problem as long as there not tough and green. PS: older combines have increased price in our area due to higher grain prices.
I have two 1680s one is a 1992 and one a 1990 with both around 4000 hours with specialty rotors for beans and rear wheel asist. The 1992 is all rebuilt with cummins engine, new hydro, replaced rotor, rebuilt drop boxes and very nice condition. the other has many new parts but has none of the majors done yet. Do not buy one for beans with out the spec. rotor it will close to double capacity! These machines must sell moving to cat.
81 1480, 2wd, no heads, a little sheet metal damage but mechanically sound brought $5600 on a consignment sale a couple weeks ago. 1480 will handle a 25 foot O.K. We push a 24 4 MPH or so when the beans are tough, 5.2 when the going is good. It really doesn't matter what they yield as much as what the stems are like. Chads