The desk: Rather than invest in a sit-and-stand desk, I lifted my desk up off the ground on stacks of copy paper. Although it's currently 6 packages high, it feels pretty stable. I don't think I'll hide under the desk in an earthquake, though. I also raised the desk up to its full height. When lowered to its lowest height it still functions pretty reasonably as a sitting desk, so I can revert if desperate.
The treadmill: I purchased the TR1200-DT3 treadmill base from LifeSpan Fitness, and it seems to be working well. I placed the base under my desk, and the associated small console on my desk. It only goes up to 4 miles/hour, but given I'm currently walking at 1.1 miles/hour I'm guessing that's plenty fast. I like that it is quiet and that it is low to the ground.
I've only walked 3500 steps on the treadmill so far today, and am already feeling a little creaky. My target is 10,000 steps a day. It will probably take some time to get used to walking so much, but I guess that's why I'm doing it, right? At least I haven't accidentally fallen off yet.