I was chatting with @Machines earlier about scoring a bargain. We both had - though his was the better score, I'd say.
I tend to use eBay, Gumtree, Preloved, Cash Converters, Cash Generators and Reverb. Only recently started using FB - check these out regularly and I'm sure you'll find what you're looking for - people are skint at the moment so liquidating their assets.
Keep looking there is something out there for you.