It all comes down to how your going to be using the keyboard, how much juice you have like extra batteries and how much money you have to spend.
For a solid keyboard for a decent price I'd suggest the Dell Foldable keyboard. If you want to conserve on battery power or simply don't want the price of BT, I also suggest the Dell Foldable Keyboard. They go for $69 on Dell's site but you can find them a bit cheaper here or on eBay. PM me if you'd like to purchase mine. You can also look in the classified section.
As far as those $20 IR keyboards are concerned, again, I don't know, but the one IR keyboard that I tried was huge, heavy, bulky and wouldn't connect to either my X3i or X30H. It was the Targus IR Keybaord so be weary if you're thinking of buying that one.
Also, in general, you get what you pay for. A lot of those old IR keyboards are for Palm devices and some don't even support Windows Mobile 2K3 or Second Edition... double check and then triple check that it's compatible and definitely check the manufacturer's website for updated drivers. If the drivers on the website haven't been up dated since year 2003, well, now you know why that IR keyboard costs so little: it's no longer supported and discontinued. Good luck getting help or a warranty for it.
I still suggest the Think Outside BT keyboard for those looking for a wireless solution: just know that you will be sacraficing battery life unless you have extra batteries or a ready power source or only planning on using the BT keyboard for short amounts of time. You can find a very good review of it with lots of pictures right here on Aximsite. Go to the review section.
BTW: I just checked out that link for the $20 IR keyboard
http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MEWA:IT
DO NOT GET THAT KEYBOARD! It clearly doesn't support any Axim outside of the X5!! Go check the official website and maybe they've updated the drivers but most likely that particular model has been discontinued. I mean the X3 has been out for almost 2 years now and they don't even support that or the X30 which has been out for almost a year! If they haven't updated the drivers by now, I highly doubt they ever will.
Just my 2 cents...