I agree. IF they were really reselling the things, the people buying them must be dumber than rocks paying that price when they could go to their local Walmart and pay less. If not terror, the only other thing would be drug trade, which also uses these type of phones.
Not only that, but they were removing the chargers and other packing/instructional materials. Even if you're not aware of the Wal-Mart price, you'd have to be really dumb to buy a phone like that at that price.
What's not so clear is that they were up to terrorism - drugs for example would be about equally plausible given the information we have. What's not plausible is that they were actually planning to sell them.