Noglider: Guys like you are in a particularly tough spot, because visual (edit: my reading of the word "software") and audio materials are so common and easy to steal these days that people justify the theft based on the ease of the transaction. Despite being a talentless hack in both regards, I fully support people in your situation.
On the matter of the catalogs, I tend to agree. The material was produced with the intent of displaying the products to enhance sales. Given away for free, it's promotional material. That you use the catalogs to alert others to the provenance of their 1972 Raleigh Grand Prix's (how is this pluralized?) probably only helps the reputation of the present supplier. But to copy a book that was meant for sale is far beyond fair use.