You can still get a lot of items through XL-Recordings themselves. Also pay a visit to CDNow where you can find maybe some other items too.
But what I mean by collecting is something else. I collect everything by The Prodigy and related artists. Not just all the albums, singles, et cetera. I collect promotional copies, acetates, white labels, covers, et cetera.
like I wrote above and download that list there and you will see what I'm talking about. The list is a Microsoft Word document, ZIP-ed, so only a few KB's big.