Mejames is correct about the Data and Data II using discontinued mechanisms. This was confirmed for me by Ed Deitemeier with Theta Digital. He said they were looking for sources for the Phillips CDM-9 which the Data uses.
I bought a used Theta Pearl 5 months ago for $600 on Audiogon. I like this piece very much. It uses the Pioneer Stable Platter as do the Jade and Miles. At the time of my purchase, Pioneer was still manufacturing this mechanism. However, someone stated here in the forums recently that Pioneer had stopped production of the Stable Platter. I haven't confirmed this, so I'm not sure if it's true or not.
Either way, Theta makes a very good, affordably priced [used] transport. And the others mentioned here are definitely worth a look too.
Good luck and happy hunting!