The Camhead generation like your 2012 are very desirable IMO, however the R12R is a niche motorbike (vs. RT or GS) and typically takes a while to find a buyer.
As far as price, I pretty much agree with the folks above the sweet spot is probably $6K-$8K, you can start at $9K-$10K with the farkles and great ad & pics but you'll probably have to negotiate down. The next generation 2015+ Liquid Cooled R12Rs can occasionally be found below $10K so that's what you're competing with. Both generations have their strengths and fans, but if you push too far into LC price territory you're probably going to be waiting a while to sell.
As far as farkles, if you decide to remove & sell them separately, shipping fees for larger items - seats, bags, shocks, mufflers, etc. - are outrageous and getting worse. The bigger & heavier the box and farther the destination the more it's gonna cost you. Really eats into your farkle selling profits. If you're in the middle of the country it'll be less, but if you're on one side and the buyer is on the other it's going to cost you. I think I paid ~$150 to ship a seat from Tennessee to Colorado last year, if I could have boxed it smaller it would have been cheaper, but still. Plus extra wrenching and dealing with buyers. Not trying to discourage you but sharing my experience FWIW.
Be sure to list your bike here, as well as Cycle Trader, ADVrider, BMW MOA (if you're a member), IBMWR (can't hurt), Facebook Marketplace & Craigslist (I know, I know!).
I wish you the best with your health, selling a great motorbike and giving up riding is something none of us look forward to.
Best! Dave