Makes and Models are Important. Anything of a 3x61keys/32 Pedals size might be of interests to a VPO (Virtual Pipe Organ, i. e. a Home Made Digital Organ using software such as Miditzer or Hauptwerk), basically Gut the organ and use new Electronics, especially if the organ has or can be fitted with Sendyne Stop Actions. Older Allens Rodgers, Very 65x Conns, Early Baldwins and others of this class.
I made a "Trick Coupler" MIDI Controller out of the Upper manual of a 1957 Conn Rhapsody. I like a certain gadget on a Conn Caprice Spinet, that I cut in Half and added to a rack ofother analog keyboards (including a Fender Rhodes, a Hammond Extravoice organ, and hopefully sometime in the future a Hohner Clavinette).
Tone Wheel (Console Sized 2x61Keys 25 or 32 Pedals with "Waterfall" Keys) Hammonds are probably the most Valuable as is, Especially a B-3, followed by different Cabinet Styles (Such as C-3's, RT-3s, D-100s and A-100s), Next older ones like E's B/C/RT-2's, B/CV's, RT's, BC's D's, A's, Etcs. The Later Tone Wheel organs with overhanging keys (and more features and Self Starting Motors) are less valuable, but still have some playability if functioning properly (many of these lived in Upper-Middle Class Living Rooms). Spinets are less valuable. The "M, M-2 M-3" (but not M-100) models are next inline (they can at least be used as donor parts to keep a B-3 going) I have an M-3 that lives in my van for gigs. The M-100, L-100 T-1/2/3/4/500, XTP and Porta-B are less valuable, the M-100 Motors and Matching Transformers can work on a B-3, but the keys re different. Some of the Oddball oscilator instruments that Hammond made have a "Specialty" Market, these are the Solovox, Novachord, Extravoice and S Series Chord organs. The balance of the Hammond line is comprablr to other Low-Mid market builders (Baldwin, Lowery, Thomas, Etc.) even if they have Drawbars like the TW Organs.
Leslie speakers are something that accompany electronic organs. The Built-in Leslies that started appearing with organs in the late 1950s are often of interest to Guitar Players, or someone looking to build an extra portable Leslie for a Keyboard Setup. The Motors can often be used to replace ones in Leslie Cabinets (2 Speed Modifications and replacing failed motors). There are Leslies intended for Hammond Organs (122, 22H, 21 H 31H) and other makes (147, 247, 47W, 46W, 31W, Etc.) can be made to work with TW Hammonds, and others (like the 101GK) that I've only seen used with a Hammond when stripped bare and rebuilt as a 122.