Russ,
Well - I think you've come to the right place for your general Axim questions! :)
First off - to be honest, don't order memory from Dell's website, you'll pay through the nose! It'd be best to search somewhere like
http://www.froogle.com/ or
http://www.pricegrabber.com/ to find the best price.
The same goes for keyboards - there are a lot being developed for the Axim, and your best bet is to search for and then post a message if you don't find any recommendations, on keyboard selections for the Axim. Once you're done, go hunting for the best price available.
I can assure you that, unless Dell gives you a 60% discount - you'll save a TON by shopping around.
HTH,
Nick