We use a Talon 7 disc duplicator in our office. It doesn't require a computer to drive it, so it's standalone. It also has a hard drive built in to store some frequently burned projects. The only thing I would recommend is to not keep it on 24/7. It's been a little buggy for us from time-to-time, but we use it several times a day and it's on at least 5 days a week. If we reset it, most of the bugs go away. Keep in mind, it won't copy copy-guarded material, such as commercial DVDs.
One more thing to keep in mind. Some of the duplicators require that you purchase specific discs to use with them. Usually they are from the company and more expensive than normal DVDs or CDs. The Talon model we purchased uses regular off-the-shelf brands.