I mostly obtain slide rules from local flea markets and antique stores. I also have purchased from eBay, but I am not a sufficiently serious collector to follow eBay. The outcome of my laziness is a dearth of the very high-class slide rules I find on the sites of other collectors. On the other hand, I just like them in almost any condition. I only recently tapered off from buying almost anything I saw.
A side effect of my indiscriminate buying habits is my collection probably shows a representative population of what was commonly used by high school students, undergraduates, and working engineers, in the region where I live (Southern Ontario, Canada).
Since there is very little in my collection that isn't already available out there somewhere, represented by better photography and narrative than I can muster, I thought what I'd put here are the portions of my collection that I can frame stories around.
I have sections on Advertising or gift slide rules, slide charts, and unusual items. Also, I put up a page on slide rules as status items.