Thanks to all who replied, and tried to help me find an Downtube.Mini.
I was finally able to track one down, and it should arrive some time next week. One of the dealers listed on Downtube's website had a 2009 demo, and sold it to me at a $50 discount. Because it's a demo bike, they've already checked it over and adjusted everything properly, so I don't have to take it to my LBS for a once-over.
They told me that they really weren't supposed to ship any Downtubes (something to do with their agreement with Yan, I guess?), but since the Mini has been discontinued and they won't be getting any more, they would ship mine out. It should go out today. Been busy this morning buying lights, mirrors, and a cycle computer for it. I also plan on replacing the tires with Big Apples, and installing some Speedplay Drillium pedals.
Once again, thanks to everyone who replied and tried to help me find one, and good luck to the rest of you who also want to buy one or sell theirs.