I doubt you will find a
better source for a foreign SIM card than Telestial but I'm certain you can find
cheaper sources. If he just waits until he arrves in Rome it will be much cheaper. Last time I was there they had a TIM kiosk at the airport (FCO).
If you must buy it before he leaves you can check out
www.cellularabroad.com or
www.SIMphoneE.com but I think they all charge about the same price.