Since I'm new to the LD world there are some discs which fetch impressive premiums and I'm not 100% why. I know pretty much anything released in 1999-2000 is rare so probably not that many were actually manufactured or sold. There's the not released on any other format discs and infamous recalled titles like the Criterion Bonds or Prince of Tides.

How about Golden Age of Looney Tunes: Vol 5? Why does that title sell for more than all the others combined?

Golden Age 5 was released in 1997. By then, box sets were pressed in extremely limited quantities even by laserdisc standards.

There's no reason volume 5 should still merit high prices. The thing that made that LD valuable was that it contained the "director's cut" of the cartoon Hare Ribbin', the one where Bugs shoots the dog, rather than the theatrical release where the dog commits suicide. It also contained WWII training cartoons starring Hook of the Navy. All those bonus features found their way to the DVD collections, though. (And in better condition.) The rest of volume 5's contents featured cartoons mostly from the 1930's, and some of those haven't shown up on DVD yet. The quality of the early thirties cartoons aren't up to the high standards of the '40s and '50s Looney Tunes, and most are only interesting for historical reasons.

The discs:
Side 1, Black and White Classics, features several cartoons from the Harman-Ising era
Side 2, Early Avery, features early cartoons from Tex Avery
Side 3, Freleng Follies, has a number of cartoons from Friz Freleng
Side 4, Musical Madness, has several musical cartoons from the 1930s
Side 5, Pesky Pets, features cartoons centered around animals normally kept as pets, including several Curious Puppies cartoons
Side 6, Objects d'Art, features "objects come to life" cartoons
Side 7, Animal Antics, features cartoons driven by all-animal casts
Side 8, Supplement Material, features the bonus content