This doesn't make any sense at all to me. I found 17 of the $20 models at the local Wal-Mart and a number of the others. Ebay has a number for less. What in the name of tarnation is going on here anyway?
If the terrorist cells are gearing up, there are several ways they could play this...
Untraceable phone communication (disposable phone to disposable phone).
A D-Day "mother of all battles" set of terrorist bombings in one day.
A long series of "lone nut" bombings.
At any rate, you can bet that such phones would become much more scarce in America after a domestic terrorist bombing campaign began. They could very well be stockpiling now for when that day (which may never) comes.
Obviously these people want to stay below the radar. Ebay requires you have an account to pay and a shipping address.