PDAs as a stand-alone item are a dead product outside or industrial apllications like Symbol. If you look at Palms web page, they just list the Pre and Pixi. And that is from the godfather of PDAs.
If you want an older PDA only product, check ebay.
This link has pretty detailed instructions on how to fix a Jornada, but involves a lot of work. http://forum.brighthand.com/jornada-560-series/216687-repair-565-a.html