You can't do the 30W HID with battery and smart charger for $250, not if he's going to have a taillight as well. The taillight is pretty important too.

I'd recommend the 13W HID from batteryspace, that's what I have and I wouldn't do anything less if my budget supported it. They have a full ready-to-go system for $185 helmet mount, $199 handlebar mount. Here's a link:
http://www.batteryspace.com/index.as...OD&ProdID=2377

That and a good rear light, a Cateye TL-LD1000 (or two if they're on sale) or a Flare or something will set you up pretty well. Be sure to spend $5 and put a good big reflector on the back; go get a 4 inch truck reflector and mount it on the back of your rack. And slap some reflective tape around your bike and helmet.

I personally like an actual Xenon strobe on the back, which are about $10 at All Electronics (the amber one is preferred by most here). That does mean some extra wiring for you since it needs a power source. Or Lightman makes some self-contained strobes for more money. To go all-out, wire in a nice red Nova Bull on the back. That'll impact your budget though as they're about $60 for just the fixture.