If you want to find inventory, sometimes the best method is to go find it yourself--even if it takes you to Moose Jaw.
Sports card sellers used to set up shop in hotel rooms across the country, in search of what might be out there.
A little pre-visit advertising to get the word out and sometimes they'd come home with boxes full of vintage sports cards that were just sitting in someone's basement or attic. Usually for a song.
That's not always possible anymore. eBay makes it easy to sell but if you're not inclined to stick your stuff online, sometimes you go see the Chartrands.
The Canadian father-son team spends months scouring the country for attic finds. They were the ones who pulled the early 20th century Sweet Caporal Hockey set out of the woodwork recently. Not every stop is full of treasure but there's enough out there to keep them coming back for more, according to a story in a Saskatchewan paper.