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To some extent such unique instruments, when in good condition, sell for whatever you can make someone who really wants it, actually pay to have it.
However, you might want to seek and look in the Organ Blue Book. It could have pricing, as well as a lot of other information.
The reason I say it's a unique instrument is, in the course of 'nature', or normal use, an organ from decades ago or 1/2 century ago, deteriorates. Refurbishing may do various things to such an organ, and what it does to it varies. So it's essentially fairly unique if it is refurbed and maintained to being still in good working order. That alone raises the price - to someone who is not just looking 'to buy some organ'.
'Standard price'? anywhere from $300.00 to $X,xxx.00 - or perhaps even more, if you're selling to an affluent person with an impulse to buy unique quality (but such buyers are rare.)
In any market, you should present everything that might dispose a buyer to actually like the actual qualities of this individual case of antique and refurbishment. A sound sample, posted, of the organ playing? Photos, of course! Description, amounting to what the organ as it is can do, in the way of playing, voices, manuals, octaves, etc. etc.