From your cost analysis, you've seem to have found it cheaper to go from a contract phone (AT&T) to a Pay As You Go PAYG service (Tracphone) even though you are using more than 3000 minutes and almost 2000 texts per year. The opposite would be true in the UK.

An example would be a T-mobile 18 month contract for about $50/month.

This would give the following,

A Nokia N95 worth over $500. (but locked to the Service Provider)

700 minutes Phone use per month. (very expensive though if you were to go above this monthly limit @ $.50/minute for phone calls)

Unlimited Texts.

1 Gbyte Internet Download @ $13/month or
3 Gbyte Internet Download @ $21/month or
10 Gbyte Internet Download @ $37/month.

Total Yearly costs would be

$600 with just the phone and text package.
$756 with phone, text and the 1Gyte Internet downland package.

The AT@T costs seem very expensive, was the cost of the Blackberry included in the contract i.e. is the Blackberry locked to the AT@T service? Can you get the Blackberry to work with the Tracphone service. I would assume that you could if the Blackberry device is unlocked.