We use a dedicated server. It's a fairly basic machine with a single Xeon CPU and 32GB ram and a lot of drive-bays, which I think doesn't cost much. It has at the moment 16 x 3TB drives in it in RAID 50. RAID 50 is not super on performance, but fast enough to saturate gigabit in sequential operations (which backups are). So it has 32 TB of useful storage for a price of around € 700 per month (leased server at a high-end hosting company, so could be much cheaper if you buy it yourself or use a cheaper provider). Per TB that's around € 21.5 per month. Although our reasons for doing this were not based on the prices of storage in the cloud, it was based on having the data on our own machine with disk encryption and only a connection to our internal management network and not the public internet.