Give it away or sell cheap...to someone who will appreciate it. Does your friend, sister, cousin, mom, etc admire your ring? Is there a local (or online) accordion community where someone might be interested in yours, possibly a student looking for their first (or their teacher)? (I took acoustic guitar, I don't know how accordions work!)
You may not make your money back, but you'll get goodwill, and the new owners won't have your negative emotions attached to these items so they will be able to enjoy them more.
I had this problem with clothes...I had pieces I really liked but just didn't fit anymore. No resale value (not designer, or brand name), but I had sentimental attachment to some of them, so I hated to give them to Goodwill and think they might be shredded/thrown out. Last time I moved, I started a fb group of giveaways and had friends come over to try stuff on. Lots of people took me up on it, abd left with things that looked great on them (and it was an excuse to see each other one extra time :) ). And a funny thing happened: once I started, it was easier to pile up (most) unclaimed items and drop them off.