Years ago, I stopped at a garage sale. The woman conducting it had a box of LP record albums with no price. I asked her how much she wanted for them since I was collecting LPs at that time. She told me to make an offer. I said "Ten dollars for the box," which I thought was more than generous. She became very snippy. "I wouldn't take $10 for one record!" she sputtered. I wonder if she still has them? BTW - what 'would' be a reasonable price to place on LP albums mainly easy listening from the 50's & 60's?
Vinyl records are sometimes worth a lot of money. I once ran into a guy at a garage sale that gave me (FOR FREE!) his entire box of records that he had collected which consisted of about 50 vinyl discs of European house/trance/techno stuff, all very obscure to me, but what the heck, it was free so I took it. I ended up selling the box on ebay for between 100 and 200 dollars (I forget the exact price) but it was pure profit! That was and continues to be one of my better flips.
Also, look for picture discs (vinyl records with pictures on the disc itself) and older blues music - those are usually worth more money.
Beyond that I don't know too much. You really just need to do your homework and research which records are worth money and which ones arent. For the most part, easy listening is a very common type and not likely to be worth a lot, but you never know. If its run-of-the-mill stuff then I'd see them going for about $1-5 dollars each depending on the condition and popularity.
Mike