Online stores, ebay? Where do you source old back issues you’re looking for?
(Full disclosure: run by a couple of friends of mine.)
Nowadays, Marvel Unlimited.
Back when I bought physical copies of back issues I did it in the physical world, in brick and mortar shops. It was all about the thrill of the chase for me.
If I can’t find them locally I go to eBay. I can usually find whatever I need on eBay.
Why would anyone want to read old comics?! Those things suck.
The late 80s/early 90s was when I was buying back issues. The overwhelming majority were purchased at local stores. Occasionally, I would get some through mail order. Trades were rare for regular series back then.
Several years back when I started getting into Powers, I bought the trades until I was up to date with the monthlies then bought the floppies from there. It was more about reading the material than owning the actual issues.
My LCS has a pretty decent back issue selection. I watch for older Superman and some X-Men stuff in the quarter bin. I also use Marvel Unlimited and ComiXology as I’m mainly concerned with reading the stories not collecting the issues.
My local (full disclosure, the owner’s a friend), Asylum Books and Games ( http://asylum-booksandgames.com/ ) has most of it’s stock online, and loads of back issues. I got the guts of Hellblazer from there. The other great indie shop here in Aberdeen, Scotland, is Plan 9, but they don’t have their stock online.
There used to be a very regular comic and card Matt in Glasgow and I used to get most of my back issues there, searching through boxes with a list:
Nowadays I don’t collect as much as read and I’ve read most of the stuff I want to, and there’s so many great new books that I don’t have as much time to consider older books.
Anything I want to go back to read I’ll generally do so digitally or in trade. If I must have the issue then it’s eBay, which pretty much dictates the value of a comic nowadays and where you are most likely to pick up cheapest.