Sometimes book collecting doesn't have to be about scouring the world for the last remaining first edition of a particular title in mint condition and paying half a major lottery win for it. Traditionally it's harder to sell hardback book club editions of books than it is to sell a good readable paperbacks. So book club books are normally - CHEAP! So when I found the books published by The Science Fiction Book Club in the UK from the 50s to the 70s and saw the fantastic retro looking covers I thought - there's a ready-made cheap and rather good looking collection to be had. The advantages of this are manifold - the books are cheap, they published, on the whole, only good books, some of which are now unreachably expensive in true first edition, and because of their uniformity they make a nice bookshelf display. The challenges are that they were made of poor quality materials and you have to be really careful to get a pretty good condition copy of any particular book and often the DJs have gone walkabout and the spines of the DJs have a tendency towards grubbiness. The SFBC used a number of different cover formats over the years (I don't go past the early 70s simply because I don't like the covers after that point). They began in the late fifties and early sixties with covers that were one bright colour and white in a distinctive 'bubble' design - most of the cover being the colour. Then they moved into a mainly white cover (these are the one's which most often have badly stained/dirty spines) and used a single colour for title, author and a rather nice 'dandylion head' design which appeared in some variation on all the covers. Then towards the end of that period they moved into DJs in what would have then been cutting edge b/w photographic designs, which still look great today.
There will, at some point be some illustrations with this post - but right now, the damn blogosphere is jammed and won't let me upload them...!