BTW, be aware that there are some LP dealers on e-Bay who are selling LPs at ridiculously high prices, trying to cash in on the vinyl revival.
If they are asking a very high price but taking offers, give then a low but reasonable number. Chances are they know they can't sell it at the high price and will accept you offer.
The worst that can happen is they will say no. You have nothing to lose.
Having said that... there are also many E-bay LP dealers who sell great used LPs at very sane prices.
Personally, I will never spend more than about $20-$25 for an LP ...used or new.
Most of my used LPs are in in the $6-$10 range and that includes some rare LPs.
Also, I rarely buy a used LP that is not NM or at least a good EX.
The key is to keep looking. Some dealers actually have no idea of the rare gem they might have.
BTW, Gold Mine prices just reflects what some have been suckered into paying for a particular LP... not the definitive price written in stone for any LP.