eBay. Love it or hate it, almost everyone would admit to surfing around the popular auction site at one time or another. It's like a global flea market that's open 24 hours a day and ships right to your mailbox.
I personally love it. I've acquired all my out-of-production/discontinued/retired Walthers N Cornerstone kits this way. Co-Op elevator, lumber dealer, roundhouse, coal mine.. Even my Russel snowplow was an eBay find. Why just yesterday I won a handful of auctions, increasing the Inverness freight car fleet. Eight 33' twin bay hoppers, three CP Script cylindrical hoppers, three 40' boxes, and a pair of these neat little unloading conveyors are all in the mail from various States;
I never would have found this neat little conveyor if it weren't posted on eBay, and yesterday I managed to win a pair of them (four pieces total) for under $20. I know one of them will look right at home at the Port Hood Co-Op feed mill, but more on that later.
The only problems I encounter with eBay, are when someone is willing to pay more than you are and you lose an auction, or a seller has posted a great deal, combined with a retarded shipping cost.
Now if Walthers had only produced the car float and car apron kits in N, I'd probably be able to find them on eBay too - but alas they were never made.