I think this was a combination of luck and persistence. The cheapest I had found otherwise were about $1000 each IIRC. I really didn't even know there was much of a market for them outside shipping companies, otherwise I would have bought everything the guy would have sold me.
Our biggest issue was delivery. The truck couldn't get into our driveway so he dropped it on the road and we had to drag/push it up the driveway with the tractors. It did a nice job of grading the drive in the process though!