We pay top dollar for Near Mint (NM) copies that still have their luster.
Are you looking to buying these records, or are you trying to sell a collection you already have?
The gold standard for identifying specific pressings and seeing real market value.
Look for "first pressings." For example, a UK Please Please Me with a black and gold label can fetch thousands, while later reissues may only be worth £20.
If you decide to sell yourself rather than to a private buyer:
Original mono/stereo copies of Please Please Me , The White Album (numbered), and Sgt. Pepper .