Here's the message text that appears in when I try and buy an app using my Verizon phone and click "info".

"Without a price plan that includes an unlimited data feature, you will incur (depending on your plan) airtime charges at applicable overage rates if you exceed your minutes bundle or megabyte("MB") charges of $1.99/MB for downloading the application. Some applications may result in additional charges for sending/receiving data during use."

If Apple were to make an Anti-Verizon sale sheet, I hope they would have enough space to include the full text.

This is why I don't buy games anymore for my Verizon phone. There's also the shady charges for accessing hi-score boards in some games when all I want to do is play the game offline.