Hoodlums has a lot of rare finds, I must say this.
I've relied on them a little shy of 10 times for a good spontaneous find and they've come through.
Though you can't go there to get the most mainstream of CD's, you can however find that CD that's lingered in your mind for the previous 4 months that you had already classified as unobtainable. Not to mention the posters that haven't been seen in circulation since 2000never (got a one off sigur ros print last xmas from the gf :D)
They offer the option to listen to any used CD before you buy, a two week return policy, and the chance to special order something they don't have.
Hoodlums is a good friend in music.
The owner is a pretty nice guy too.