I have a keyboard that I have to sell before we move in spring. It's a 1974 Baldwin FunMachine model 121W. It has all of its original books (albeit with torn covers and pages) and even the original bench. I can't find anything about it on Google, and I've only seen it on eBay once (And it went for a ton of money). I can find info on the other FunMachine models, but not this one. I take it it's pretty rare.
hmm...sounds vintage enough for you to sell it to some collectors.
I would suggest looking it up on a database of keyboards, or asking a forum devoted to keyboards and synths.