How exactly do you save them money? If they connect from Iceland to Iceland, they haven't changed their point of origin right? So any use of overseas servers would still cost them?
The size (measured in GB) of the international bandwidth "addon" determined the price of the connection far more than the speed of it.
By hosting my servers in Iceland, the traffic through the VPN would not count towards the "international bandwidth" of my users. And since I was hosting in datacenters, I would be paying less for the bandwidth than at a typical home connection.