Bulbs and Ballasts

Hey i currently have a 1000w HPS bulb that i dont have a ballast for.
its too expensive to run so im going to replace it with a small 150w bulb for now.
heres my question: If i use a HPS with a medium base, will i be able to screw that bulb into any household socket or does it need a specific ballast to work correctly?

im trying to stay cheap here, keep in mind.

if so what would you suggest for a good/cheap ballast for a medium base bulb?

you will definately need a ballast, hid lights cannot run safely off of your house fixtures. check out 1000bulbs.com they have a lot of diy ballasts for every type of light at very low prices.

alright, thats where i got my 1000w setup from actually...
and thanks for your help man

and what makes it unsafe? heat? electrical output?