Here is a link to a recent article on book collecting in The Guardian that I thought might interest you.
Ah Rick, there still can be a Santa Claus. You just have to seek him out. Find the unbeaten paths. Take your love of an idea and carry it out to the end. You will find an unending variety of books out there waiting to be made into a cohesive collection including some very scarce but not very valuable books – because you have not yet made them valuable!
– Bob Fleck