As I found out LPS (Low Pressure Sodium) lights well both LPS and Halogen lights are crap they don't produce the right kind of light and they waist power. You can go with a 70w HPS and a 35w MH bulb setup for flowering to get the full spectrum that is needed.
Also the prices are different because of the different countries that we live in but also where we get our lights and such to makes a difference. For me I spent $143 on a 70w MH , 70w MH ballast , 70w HPS and 70w HPS ballast. As for the fixtures well the fit right into the regular light socket so I was able to use my lizard light fixtures that are rated at handling a 150w heat lamp for them so I just used that.