I got the 150W ones at Lowes for $10. There's a cheaper version of same size with a basic clamp. I think the clamps are removable on that one since this one is removable. The one I have I can clamp and still position the shield. The reflectors are thin so they dent and bend easily, went through a few boxes of them before finding 2 somewhat decent ones.
I use them for cheap photography lights, the power cords on these are short and if you're hanging above you'll need some extension.