The Drobo 5N is one of the "deals of the day" on Amazon. Regularly $599, today only the price has dropped to $429 with free shipping.
I have a 5N and have talked about my experiences with the product on Mac Power Users as well as in this post. The short version is, I love my 5N. I use my Drobo for all my archival storage, a backup destination for my computers as well as several family computers and to host my iTunes library. The 5N serves as a Time Machine destination (and is faster than my Time Capsule) and I've installed Plex via Drobo Apps so it can function as a standalone media server.
If you've ever had any interest in a Drobo, the price today is hard to beat. Find it here (affiliate link.) While you're shopping, you may want to pickup a few Western Digital Red SATA drives to feed the Drobo. I use these drives in my unit and find they're fast, reliable and quiet.
Disclosure: Drobo is a sponsor of Mac Power Users