Join Date: Jun 2008
Location: Just outside Kitchener, Ontario
Bikes: Nishiki Continental, Bilenky custom travel tinker, home built winter bike based on Nashbar cross frrame
Given that extra information, your choices are basically "most" of the used market for any of the name brands. I was able to pick up a used Santana last year, for something in the lower $1000s, which I managed to keep below $1900 by the time I replaced the brake shoes, one of the brakes, the captain's stem, both sets of bars, and the brifters. Most of these were replacing what didn't work or fit. If you're interested in new, consider the Hokitika made by Tandems East in NJ (it only sounds like it comes from the far east).
In addition to what you found there are a few even cheaper models out there, and a small number of folks have been happy figuring they were buying a frame and didn't need to replace all the components - only some of them. But these come only in one size.
If looking at new, consider pricing a single bike with the same grade of frame and componentry as you would be happy riding. Expect to pay MORE than double that, but probably not more than triple. The tandem-specific components more than make up for the reduction in quantity of a few components in price.