Find your local major electrical company (like one's that do large comercial jobs) find their suppliers (their suppliers usually sell to the public, just not at our discounted rate)

**EDIT**
You can find this item legally for under $200 on amazon, under "home improvement" I found it by doing a google search for "metal halide wobble light"
and if you are really interested they come in a 100w and 175w version. HTH
**END EDIT**

But honestly if you are going to be honest and pay for it, your money is far better spent on the proper ballast and reflective hood. Those lights are designed to light hallways, not the most efficient route of MH lighting if you are growing plants.

But hey, I guess it works great if you want to take that other guys suggestion and steal it...ya know I mean free crap always works best I guess, I dunno I just hope you don't steal your supplies from hard working american men, who put in 8 hours of hard work to build America 5 days a week!!