Have you ever sold something to gain more money, only to eventually buy that something back?

Sounds like pawning. I’ve never done it before, but I sell some of my stuff on eBay.

An expensive treadmill

@dxs I definitely don’t want to pawn. Not interested in paying interest. I’d rather sell the items and no longer be the owner. Then look for more when the time comes I guess

@pleiades Pawn shops do that, too.

I sold my History of Art text book back and then instantly regretted it. I bought a copy back, but I was really disappointed the store only had used copies, mine had been brand new.

I have sold several things that I lost interest in only to regret it later when the interest came back

Pawn shops are perfect, if you want one tenth of value for your items. Some people deal professionally in albums, just as with comics, or sports cards. You may be able to find a dealer who can work with you, and possibly even set aside some of your favorites for you, if you can nail down how long it will take you to buy them back. I would advertise them, but with no cash value attached. Something like, “Seeking vendor for sale of my massive vinyl collection, in the $$ thousands.”
For a collection that size, you may have to reach a ways. Hopefully, you live in an area where collecting vinyl is all the rage.