I always troll eBay looking for Crestron gear. I usually get some very good deals.
One time I saw a seller who was putting up a bunch of card modules for a HDMI matrix switcher. I had just purchased a 16x16 chassis, so getting these cards at a good deal was something I couldn't resist. I ended up buying about 50 of these cards, with plans to resell some of them. I was getting them for super cheap. Under $100 a card. These sold new for over $1,000 each and I could easily resell them, after testing, for a couple hundred bucks each making it all worthwhile.
Low and behold, when I started testing them I saw every single one of them fail to work properly. Instead of simply returning the cards, I called Crestron (I work in the industry) and when I read Crestron the serial number, they asked me where it had come from. I let them know that it came from eBay and the guy came back and said that there was nothing they could do, but that the cards were supposed to have been destroyed. Crestron had PAID for them to be properly destroyed, and instead some sleazy company was trying to resell them.
I contacted the seller and read him the riot act. I had spend about $3,500 or so on all the cards I had purchased.
He asked if it would be okay if he bought all the cards back from me for $5,000.
So, without really doing a thing, I made $1,500 profit on cards that never worked. This was about enough money to pay for the chassis and most of the cards that ended up going into my A/V switcher that I currently use in my home today.