I like to collect catalogues from my collecting field, so really 1950 - early 1970's.
It is satisfying to see the vintage models that I own in period advertising material. Sometimes I find them cheap ( €20 - € 40 ) and sometimes a little more expensive. I think the most I've ever paid was around €65 or so for a mid 1950's catalogue that I had never seen before with many interesting references and a good 70 or 80 pages.