Mercyful fate - Don't break the oath backpatch

So here's the deal. I have this old Mercyful fate backpatch which I put in a cheap Ikea frame and which was on the wall of our living room for years. Now we've moved a few months ago and there's no more place for it. So eventhough I normally don't get rid of things, I'm contemplating selling this one. I'd prefer trading for some rare vinyl but experience tells me nowadays it's easier to sell it, then use the money to buy something rare.
The backpatch is complete, just the two upper borders were folded to fit in the frame. I know this is bloody rare, but honestly I never gave a shit about patches so I have no idea what to expect price-wise.