The Tungsten C hasn't been discontinued yet, although it will be before too much longer and the stores may have decided not to reorder what will soon be obsolete. However, you can still purchase it online directly from Palm for $399.

The only other mainstream PDA I know of with an integrated keyboard is the HP iPAQ h4355. It too is old (received the Cnet Editor's Choice award in October 2003), but still gets the job done. Unfortunately, it too is about to be retired and is not easilly found. In fact, while it's still available, HP no longer sells it directly.

HP used to make keyboards that were designed as addons for some of their PDAs, but they stopped that some time ago, and now it's rare to find a PDA that has a built-in or addon keyboard. Your best bet would be to pick up a good folding keyboard, either one designed to plug into the specific unit, or uses Bluetooth or Infrared. However, you may still be able to track down one of the PDAs that have native keyboard support.

Hope this helps,
John