I am in process of trying out a converter for my own DVD battery to provide USB power for my Sound Devices USBPre-2. Once I finish and check it out there will extra supplies and I will probably have enough parts to make a few if there was any interest. I don't know about the cost yet that will depend on what I build it in. I had tried a simple voltage regulator in the past that did not work and this is a completely different approach. Since I use my DVD battery to power a few different pieces of gear I will make it hot swappable and have 9volt and USB output. The prototype is not picture worthy since it will only be a down and dirty workable model. I'm looking for it to provide 5volts at a minimum of 500mA (USB specs), it might end up providing more amperage
But if there is interest I would chip away at a test version. I just thought since there are a lot of us with DVD batteries and maybe there are others like me that could use a USB source in addition to the 9 volt source. The Tascam 60D thread brought the idea back into my memory. Chime in if this might be something that you'd like, Kirk