II. This Ain't Discogs.
Discogs is awesome. A great resource for tracking down version details, documenting your collection and wants and for buying and selling. It can be a fair gauge of the current online market value of your record. I use it every day personally and professionally.
I repeat: Current. Online. Market. Value.
Not the Maximum Sold Value. Not even necessarily the midpoint. The closest you can get is looking at the detailed history of US sales for items of comparable condition. Even then, that's online and subject to FOMO and the like.
This ain't Discogs. Please do not come in with the "I know this is worth [maximum Discogs sold price]" expectations when selling or trading your used items. Here's the facts:
You can almost always make more selling your record yourself. That also means you need to list it. You need to clean it. You need to grade it. You need to package it. You need to ship it. You need to pay Discogs and Paypal fees. You need to deal with buyers if they're not satisfied.
I do sometimes use Discogs as a guide for value, especially for records with which I am not familiar or legacy titles with many pressings, originals of which may truly be worth more. Most often, though, my offer (and thus my selling price) is based simply on "what does this feel like this is worth?" Nice vintage copy of Morrison Hotel in super shape? Feels like a $20 record to me, I'll offer you about $14. A numbered Beatles white album? Ever see how how those numbers go? It ain't that rare if I've seen four in a month in Troy - feels like a $20 record to me. Not $200. Maybe $30 with the posters and photos. Maybe a lot less if it's beat.
I don't grade and won't quote grades. Everyone's eyes and ears are different and I challenge you to come up with a VG+ that differs from a NM that everyone will agree on. Instead, come in, open the album, put it on the turntable and decide for yourself if it's worth the asking price.
Don't even get me started on eBay.