When I first started collecting laserdiscs the thing I found most difficult to estimate was the true value of a particular disc.
In particular some music LDs would fetch hundreds of dollars and others consistently sold for as little as $10 max.
I had to literally watch lots of discs on Ebay sell over and over again to get a good feel for their real value.
I obviously made a few mistakes in the early days myself. I remember someone telling me Grand Funk live was mega rare on laserdisc.
I definitelt paid over the odds for a rather scruffy and incomplete copy of it:
Grand Funk: Live - The American Band (1974) [DLZ-0112]It is quite a rare title but definitely not mega rare - I've since seen loads of mint copies of that disc appear on Ebay over the years so overestimated how much it was really worth. In general music laserdiscs costing a few hundred dollars are common place and that particular title was just a very average title in terms of rarity - great concert though!