|The problem is that a good nas in that range also doesn't include drives. |
For a song one might be able to create a nas with raid even on some old computer with freenas or openfiler, really any BSD or linux would do. Might even get windows to work.
The part about the backup includes a job that runs at some set time usually. It should allow you to do ntbackup or other type of backup when you select and in what way.
The least expensive way is to buy a usb drive and do a manual backup each month or so. At least once a year to save some of your computer.