So you know, the going rate for a manned edit suite in your market is 250/hr and the going rate for a freelancer is around 70/hr.
I tell you that just so you have barrings on the norm, knowing you are not the norm. You are buying experince in this one, they are buying a half priced deal.
I'd say throw out a flat rate because it will take you longer than a seasoned editor by the hour.
Look at it as adding content to your reel. Any money is a bonus. Ask for 500 bucks per DVD and do em all for that price if ya have to. Then next time around you can stick your chest out a little more.