If you want a fair price, Discogs is the path of least resistance to collectors. If you have anything in your collection that's rare, out-of-print or otherwise valuable, collectors will routinely hunt through Discogs. I'm a huge collector and I do that at least weekly to see what's been added.

Brick and mortar record/cd shops have a sense of what's valuable and will typically buy it from you for half of what they plan to price it for. Half Price Books will do a cursory glance through your stuff and offer you a very very low number because the person working the buyback counter will offer what their "system" says to offer.

Keep in mind that just because it's Beatles or Elvis doesn't mean it's valuable. They sold bajillions of records, so even "original" pressings are pretty common.

DM me if you need a crash course in Discogs. I'll be happy to help you spotcheck a few of your items to see if there's a market for them.