I have to agree with ultralc. There are a few organs with a large value, like the Hammonds described above. But even for these units, if they are in less than perfect shape they are hard to move, and if they are no longer functional they are impossible to move at a decent price. In my area, two long time organ repair specialists retired in the last few years. As a result, skilled service is impossible to find.
If you have ever opened up the back of some of the older (i.e. tube) units, you would be astonished at how demanding a refurb might be. I recently had a supposedly valuable unit that died. Inside, in addition to almost 100 good tubes (over half were RCA 12AX7s and 12AU7s), and two beautiful Jensen speakers, were over 200 electrolytic caps, over 100 resistors, and many hundred wire connections (many were early vinyl-coated wires that were literally melting away).
I had a choice of salvaging parts, or replacing most of the capacitors, resistors, and a great deal of wiring. The salvagable parts were worth over $600. If I completely refurbed the organ, it would be worth $600 to $800. The organ was a classic, but the case wasn't close to mint, and it wasn't half as good (in functionality) to a newer model that would cost much less. With the dearth of local expertise the answer was simple, if for no other reason than the dozens of hours that the refurb would have taken.