For what it's worth - I have a Zire gathering dust in a drawer. The Palm software is no longer updated - there is no active app development for it, and it's been hard to load applications on it from a modern OS.
Consider watching craigslist or ebay for an ipod touch 8 GB. I frequently see them for less than $100. Much better device than the Zire... has built in wifi, and can run chess.com's mobile app.
I think I can get a decent palm Zire 22 or 71 for $25-$40, but I want to see how well HIARCS for it works first. I've read reviews and such and heard good things but I want to see it in action!
The only other option I see is going with something like an iPhone, but I'm not willing to spend a few hundred dollars for essentially what's going to be a handheld chess device, which is what I'll be using it for.