Building a 100 album vinyl collection 3 must have albums are?

@tony1954, 

You should also mention to the OP that an original, genuine pressing of Tool's "Aenima" will run at least $1000.  There are many, many bootleged versions, but very few genuine articles.  

the Shure test records (count as one)

the Denon test record

etc., etc.,

@palasr 

Not sure how relevant that is, as the same could be said for an "original, genuine pressing" of Kind of Blue, Pet Sounds, Allman Bros. at the Fillmore East, Blue Train, etc. As there was no reference to cost in the question and there are always avenues for finding good bargains on anything if one is diligent.

Oh, I forgot.

Crosby, Stills, Nash, and Young: 4-way Street