Cloud backup for Windows Server

I subscribe to the 3-2-1 method of backups.
- 3 copies of EVERYTHING
- 2 different types of media
- 1 offsite at all times

I have multiple not for profit clients who are running a client server environment (Windows Server 2003 or 2008). They currently change tapes or external hard drives for their backups. But ensuring the files get offsite in case of a true disaster really isn't in place.

Where can I find a reasonably priced solution?
SugarSync, Carbonite, Mozy all have business plans, but don't officially support the Windows Server environment. Amazon S3 cloud costs are to hard to figure out (15 cents per GB plus, 15 cents per GB transfered); to much effort to do that calculation on how often files change.

So am I stuck? So far it looks so.

There are solutions available that will let me back up the files to an offsite PC. But where do you put that? My house is close to both clients, so a tornado or earthquake could easily take us both out. Also could go to a NAS that supports internet backup (Dlink DNS322 http://www.dlink.com/products/?pid=509), but the same issues as an offsite PC.

Really need some help here.

Im an uncle

Colby Norman was born yeesterday at 1:36pm; via emergency C-section.  Mom and baby are doing fine.
4lbs 9oz
17 1/2in long
He is currently in the NICU; but should be out soon.
Welcome to the world Mr Colby