You have to read around alot on what are the most cost effective lighting systems. Expensive lights arn't always the most efficient because generally, the more powerful systems are bought by commercial growers who don't really have much concern over whether the light or ballast will be too loud or too hot, for example, because their dealing on an industrial scale, they'll have a big fuck off ventilation setup which will just 'take care of it'. Its different for a small hobby grower where these concerns are paramount. If I was you I would find the most talked about grow shop, or most commercially known grow shop and review what they have in relation to other websites and the thousands of ebay dealers. I've seen lights, well priced that offer 25% reduction on energy requirment whilst offering an increase in light output for a fraction of what just one HPS would cost at the very best quality. Check out Cannatronics, they specialise in low cost, high output, cheaper running lighting systems.