Yes, there have been some deals on the previous versions. Some friends were replacing an old iMac and bought a Powerbook (or whatever), and there was an offer of an iPod Touch for 20 quid.
Wish there had been the offer of multiples (I'd love to have one - knowing it just has wireless and would never have other charges, unlike an iPhone, would make it ideal.)
Certainly worth looking on the Apple Store for a refurbished model, Kaloki, as there would be same guarantee but a moderate reduction... though have to say I think the iPod Touch is far more flexible (playing video/music - a cut-down iPhone) than a straight PDA.
As an aside, there used to be a BT product, the Easicom 200, which was a combined phone directory / calendar / PDA type device which had a base (for charging, I think). When plugged into the base, it would load details of any new phone calls (base included Caller Display hardware, uploaded any missed incoming call details to removable part).
I bought a few (as gifts at 25 quid instead of 150) when they were being discontinued, but there might be someone selling a similar device on Ebay (you sometimes see boxed and unopened devices on there - admittedly would need some new batteries, but should otherwise be in working order).
Kaloki - if you want to e-mail me on [email protected] - I'll check if I still have one boxed and untouched :)