Where is the best place to buy a brand new cobra head off the internet besides ebay? I see prices varying a lot.

Also, AEL and GE HPS reactor ballasts are wound with copper or AL? I'm craving a 150 really badly as of late.

Check out this thread http://www.lighting-gallery.net/index.php?topic=5770.0

Thanks, but I am looking for new in box.   

Also, AEL and GE HPS reactor ballasts are wound with copper or AL? I'm craving a 150 really badly as of late.

What's a 150?

150 watt HPS cobra head. My bad for being less specific. 

Check your local electrical distributor.  They typically have to order them as they usually do not carry any in stock, but it's not too hard to find an electric supply store who could order a GE M250R2 for you.