Back in 2002ish, I was in the navy and bored while underway, so I bought a couple runs just to read. I got a full sandman run (missing like 3 issues in the 30s range) for about a buck an issue, an xmen run from 150-300 missing just a couple minor issues for well under a buck an issue, and an ASM run missing a few minor issues from 230-300 for under a buck an issue (but it included 238, 239, 252, 300) for under a buck an issue.
I really wish I had bought more back then, as each run I bought had books in then worth well over what I paid, but I was distracted by a little game called warhammer