People. You are not going to like my saying this (what with my being a supporter of DYI while avoiding corporate sponsorship like the plague), but I stand by my advice here. For getting all sorts of old recordings that have recently been rereleased on CD (and there have been lots, from the Slits to the Adverts, plus more compilations than you can shake a stick at), I have not yet found a better source than the multinational, big corporate chain ...
Yes, friends and neighbours, with over 75 years of music retailing history and 275 stores worldwide, HMV is the world's premier retailer of music. Currently, HMV's international operations include stores in the United Kingdom, United States, Ireland, Germany, Australia, Hong Kong, Japan, Singapore and Canada.
OK, now this is way I do it: go to HMV and tell 'em what you want. They look it up for you, and if it is currently in print and therefore available, they'll order it for you (no money up front). When it comes in - which can be anywhere from two to 6 weeks - they call you and you swing over to pick it up at the regular store price. There are no special fees, no ordering charges, nothing extra (at least's that's been my experience with them in Ottawa). I know they're big, but the service is great. I also know that now you can also order stuff from them online and all that, but I don't do e-business over the web...too risky... Anyway, I prefer the personal contact. Yeah, my age is showing here.
One other mention: if you are looking for original vinyl recordings, these may be very tricky to track down. Personally, I prefer CD's but that's just because I am lazy (i.e. you don't have to turn a CD over - you get some 45 minutes of non-stop music, but I digress). I know that there are purists out there who shudder at the thought of punk on CD, and for those of you my suggestions are to:
Good luck!