So building your own light question

I was looking at building a small hps light and saw the mogul sockets that you can just plug a light into, I only have a small space... the size of lets say...a fridge. What im wonderin is.. does the ballast system on larger lights reduce the energy consumption, and can these mogul sockets be used for larger lights, let say 250watts. What is preventing you from just plugin in to a mogul without using a ballast?

The ballast is actually a necessary element. It primarily provides the optimal electrical output to power the special bulbs, and secondly, the ballast provides a constant current to the bulb (as opposed to voltage)
There are also Low Pressure Sodium (LPS) lamps on the market, that can be run without a ballast.
I am not sure though, whether or not these are suitable for use in gardening.

I am using CFLs on my grow at the moment, and can't say I have a single complaint thus far!

You can buy the gear (Ballast etc) for a HPS on ebay for about $50

Good luck!

P.S Low Pressure Sodium lamps are generally used the world over for street lighting