Mozy is one of the most affordable online backup solutions on the market. Their Pay as You Go Model is easy to understand and offers value for money.
Server Licenses: $6.95 + $0.50/GB per month
MozyPro can be a nice, inexpensive addition to a backup program. It's one of the most end-user-friendly systems.
However I found myself working many, many issues where backups didn't complete or were slow.
This was in 2009. Newer versions may be better but I wasn't impressed or confident that it was working or recoverable.
While not terribly easy to setup on the mozypro side, the software itself is very easy to use for backups as well as restores.