Upgrading to BB 8310

Hi,

I've almost decided to upgrade to BB8310 (rather than to Iphone).

I have 1 more month to end my current contract. An upgrade now (keeping my current plan and signing up for a 2 yr contract with a data plan) would cost me $199 for the BB 8310. But when I looked at websites like letstalk.com, I can get a BB 8310 for $24 for a new activation (2yr contract and data plan). But this would mean a new phone number..I would like to keep my existing phone number. But with the price difference, I'm in double minds.

a)Will I be able to get a better deal for upgrade once my current contract expires ?

b)Has anyone bought their BB 8310 from letstalk.com, if so howz the experience ?

c) What is the lowest data plan (AT&T). ?..(I hear both $29.99 and $39.99)