you will need a data plan as well to go with the device. Nextel will force this on you. Unlimited plan is 49.99 per month on top of whatever your voice plan is.
Cases, chargers, data cables, well you can find those anywhere.
but then again, I would have to agree, this does sound funny, if my freind who worked at a Nextel store just gave me a BB and didnt tell me or give me anything else