Is there an offsite service i can use where a 3rd party will keep my dvds for me?
For backup storage, a safe deposit box at your local bank is always a good option. An added benefit is being able to store personal files and valuables.
Encrypt your backups!
Now any closet/garage is a 'secure off site location'
If this is for a work setting, this could be pretty fun. Just mail the monthly (encrypted) backups to your bosses house.
Dear Mr CEO, I am this months backup dvd's. Please place me in the box in your garage with all the other dvd's. But remember, I am the sum total of your digital assets - I am worth <insert large million dollar figure here>. So look after me. Regards - dvd #1232
Depending on where you live, Iron Mountain provides secure offsite storage, recovery, couriering, logging and delivery, as well as a bunch of other services in this realm -- from paper shredding to online backup. No I don't work for them, and have no vested interest to disclose.