When I started acquiring enough pipes to have a 'rotation', it was through ebay estate purchases.
"Winning" an auction for a desired pipe is in itself a bit of a thrill, but one you should put into perspective.
Old pipes require cleaning, but they're durable old things that have been road tested, broken in, and still have what it takes to make your tobacco sing.
Put yourself on a budget, don't exceed a certain price level, buy typically known brands.
My first ebay estate win gave me a batch of corn cobs, some used, some new, and one which turned out to be a meerschaum that only LOOKED like it might be a cob.
The next one provided me with a few eminently smokeable no name type briar pipes with which to begin my education concerning briar and things like stingers, airways, bowl sizes, finishes, shapes, stem materials, and the fine points of 'buttons' and slots.
I've got a bunch of brands now, including Savinelli, Comoys, Butz Choquin, Stanwell, Peterson, Barling, Dunhill, Ascorti, and more, but I find myself going to the older models made by Grabow (and cobs) most often.
Pipes that have been gifted to me will also receive more love, because of that 'connection'. Brand is secondary, performance is primary.