I'm just trying to help you set it up so you will be pretty safe and set for the next 3-5 years. $500 extra as a one-time investment with 3-5 years write-off will help you avoid downtime (make it orders of magnitude less likely), and keep you from loosing data between backups if a drive should fail. How trivial the consequenses may be, it's nice to be safe. the $100-150 pr year for one (or more) order of magnitude better safety could pay for itself in avoided losses should you win the inverse lotto. :P
While we're on the subject of safety, do you keep off-site backups? And do your on-site backup have redundancy?