They used to have one for $20. I got one last year just before they stopped selling them. Wish they would bring those back. They were easy to gut and work just fine for what we want.
I got my bulbs at HD, for 20 a pop. And then the ballasts I took off of those clamp light casings, they have fitting 150 compatible ports that are SUPER easy to get out of the reflector. The clamp reflectors were 20 a pop as well but it beats the shit out of paying 100$ for 2' of wire and a few diodes.
best deal on a 150w hps ballast kit is on businesslighting.com
if thats not the exact site, just google business lighting. Can get one for about 50 bucks i think.