We install Backupbuddy on almost all of our client WishList Member (and other) membership sites, and advise everyone to setup an Amazon S3 account to use for remote backup storage (among other things).
Here’s the link to open an account: http://aws.amazon.com/s3/
Amazon S3 is a simple web storage service that gives you the ability to store just about any type of data in the cloud. For this reason many membership site owners use it to host videos (it’s rarely a good idea to host them on your website) audio files, images and backups. Amazon gives you the first 5GB free and additional storage is very inexpensive. In fact services like Netflix and Smugmug use it to store and serve their files.
While it’s not difficult to setup an account it’s a little geeky. Here’s a video that walks you through the account setup and connecting it to your Backupbuddy software.