Well, you could always try Ebay, but it’s a hit-or-miss proposition. Unless you’re really in need of the cash, you could keep it & the speakers for future use, maybe in the space where you found it? Or, if you have kids, they may want it for music playback.
I have found myself in several situations where I’ve though “man, I wish I had kept that old _____. It would come in real handy right now”.
I have an older HK receiver & AR speakers in my basement waiting for us to finish the basement & use it as a secondary HT setup.