My first thought when reading this story was... who ordered that much stock of these phones? As you point out even at 100/each they would've had to have had hundreds of phones in their inventory... I wonder if they were all the same brand/style or whether he bought out ALL their inventory.
Seems to me like a LOT of phones to have in the stockroom, but then I'm not familiar with Target's ordering procedures/inventory management...
I think when you buy them you can fill them with as many minutes as you want. So this could be a very few phones with lots of minutes each, or lots of phones with just a few minutes.
If you've ever had a teenager in the house, you know they can burn thru 2000 minutes in no time.