I used to work for Tmobile when smartphones were more exotic and lacked wifi options (think sidekick, blackberry, palm, and windows) and this guy's international roaming wasn't that high compared to some of the bills I've seen. I've seen $25000 US bills just from messaging while traveling internationally and some customer that called in to ask why his bill was so high when he was roaming on an oil platform (at the time this was $9.99/minute call). I consider international roaming another form of raping people's bills from all the carriers both foreign and domestic.
I highly recommend for international customers to use an unlocked phone, rent a sim, use wifi as much as possible, and use messaging/voip apps to stay in contact while traveling abroad to keep costs down.