Depends- it was awesome to discover my $1 in-box copy of Wolfenstein 3D for SNES was worth notably more than a dollar... but Wolfenstein is not a favorite title, so it got shelved pretty quickly. Picking up a copy of Magic Knight Rayearth for Saturn within my budget, though? I played that all they way through after I got it, becuase it's been on my want list since I was 12.
I don't worry about it much, becuase it's nice to come back later when I can't afford to be making new accquistions, dig though the backlog, and get excited all over again when I find something good I'd put away.