I'm also looking for some helmets, there's a pretty wide selection to choose from. I don't know exactly what type you have in mind, but if you want to attach lights to them, some of the helmets don't hold a headlamp very well. Maybe to look into a caving type helmet.

http://karstsports.com/helmets.html

If price is a main concern, you can find some really cheap skateboarding helmets for less than $20. They're a little heavy and hot, but they're better than nothing.