Well, a different perspective for you:
I bought mine just before my first year and love it. I use it often, every single day. I have 8+ different references (e.g. Taber's dicitionary, 5MCC, epocrates, lexidrugs, interact, medical mnemonics, eponyms, a really awesome spanish/english dictionary, plus a host of reference documents and much more that I can't think of right now. I have a 128 MB expansion card, so I can carry everything I could ever want). I am always looking things up right when I need to know them, whether in the hall or in a class rather than waiting until I can come across the paper versions. It has dramatically increased the speed and efficiency of my learning. Of course I also use it as an organizer (since it fits in my pocket, which my Franklin did not do) and it also plays some really fun games when I need to burn some time waiting somewhere.
All technology is a consumable, if you are looking for something that will stand the test of time, buy a diamond or something. The handheld market fluctuates the most right now, if you buy a handheld now, you will buy another in 2 years, and another two years after that (maybe sooner) That's just how the game is played (look what was available two years ago compared to now). I have a little more than $300 in my Visor Prism (minus software) which is NOTHING compared to the $500 I dropped in coursepacks and books for this semester alone (last semester was $1000 and forget about the $100K+ I'll owe in the end), and use it much more than any of them.
Also, there is a bit of a learning curve with these things which takes time. They are very powerful computers that have tremendous capabilities if you will take the time to learn how to use them (will you have more time for this during the clinical years?). For instance, the Grafitti for Palm OS is easy to do right away, but only after a few months have I begun to really fly with text input. I would rather learn it now and be really good, and know the software that I like and be good with it BEFORE I need it for my patients. Will you wait until you clinical years before you learn your reference books, or would it be better to know your way around them before it really begins to matter? It is certainly up to you and what you think is best.
If you will use it, buy it. In the grand scheme of things the cost is miniscule and the benefits are great (unless you don't use it). The Prism is a great deal, and very expandable (like I said, I have 128 MB of storage on the expansion card in addition to the 8 on board, which will take a long time to fill up).
Best wishes.