If you want to be cheap, here is a solution - install the software on a second machine at a separate location (e.g., friend, in-laws, etc.). There is no charge to backup to another computer. I maintain a backup of ~100GB in this manner using CrashPlan. To speed up the initial transfer, I temporarily put the two machines on the same LAN. Once the transfer was complete, I moved the machines to their permanent locations. Now, any updates (e.g., photos, documents, etc.) are backed up easily and quickly since the total size is not that large on a daily basis.