Metal Halide Hi-Bay Warehouse Lights
 

Has anyone tried using warehouse lights for hydroponics?
You can get them on ebay for about $100.

I would have to build or find a better reflector then what they come with. Or maybe cut the reflector in half and hang it sideways.

I worry about how noisy they might be.

Absolutely. I've got two MH 400w lights made from high bay ballasts. If you follow the link below you can see a few pictures I took. I removed the lens and hanger assembly and removed the ceramic mogul socket. I bought a commercial horizontal reflector that had its own mogul socket built in. I also bought a horticultural bulb. Then I wired it all up. If you use a high bay ballast, make sure it has 120volt taps if you plan to use it with standard wall power. I got the idea to do this from a guy on this website! Saved me a lot of money. You might be able to use the high bay reflector for more savings, but I wanted something better looking since this all lives in my florida room and I wanted a glass cover for extra protection.

Pictures here:

Hydroponics Warehouse Lights

is used a warehouse light too, great solution that only cost me $60
Craigslist... $30 for the light and $30 for the bulb
why spen over $200 on a good light when you can get the warehousing lights for next to nothing.