My deaf friend has a Blackberry Treo 700, and it looks very nice. It is a little older model. A new BlackBerry Treo #? is much smaller screen and it does not look good. You could try the Treo 700 for a lower price because it is "old version."
I am aware that many deaf people are bored out using same SKII for a long time. They want to try something different model.
I personally like the iPhone, but it is too expensive and plus too expensive to pay monthly like 60 dollars a month. So, I think that BlackBerry might be worth it.
P.S. I just checked on a Google for Treo 700. I am confused now, and I thought that it should be a black pager. I am looking a wider screen. I will ask my friend for the confirmation.