I have a Night Owl Explorer (model NOCX3) that's battery powered and has a built in IR illuminator. I was originally thinking about the hand powered one, but realized that you can't use it hands-free like the battery powered version, it has no built in illuminator (needed for indoors), and mechanical movements can break, electronics are much more reliable.
The only real problem with it is that the illuminator isn't totally invisible. When you're looking straight at it you can see a bright red spot of light (which is a perfect aim point for your head), but the scene you're illluminating isn't visibly lit, so if the BG isn't looking straight at you you'll have the drop on him.
But I obviated the illuminator problem by converting a BRINKMANNs LED flashlight ($12, Wal-Mart) by replacing the visible white LED it comes with with a hi-output IR LED bought at Radio-Shack. Totally invisible and lights up the scene for at least 30 yards.
You can use the same converted flashlight as an illuminator for your NVD, velcroing it on.