Professional Electronic Repair Service Since 1978
Tips to sell your organ
If you would like to sell your instrument you might try listing it with CraigsList - it's free. Other free options are Facebook Marketplace and OfferUp. Be sure to mention the "make" (manufacturer) and model of the instrument in your listings. Pictures would be very nice too.
I do not know of any company that buys used organs for parts or resale, including me.
Once, in a while, you might find a dealer that will take an exceptionally fine instrument on consignment but that's about it.