The cheapest way to build up more crates is to grab piles out of the fifty cent bin. After sifting through hundreds (thousands?) of Barbara Streissand records, the obvious method is to pick up anything you're already up on or that just looks interesting. You will start to realize that the same artists frequently end up in these bins across the nation. This thread will hopefully feature regular additions in a list of artists to look out for that both appear and belong in the 50 cent rack at your local spot. Feel free to add your own if I don't already have them.
50 cent bin legends: Ferrante & Teicher
Prolific library/soundtrack duo you should know about, not the best for listening but to a sampler, sound as good as the lp you picked up for 10$.