There are very few shortcuts when it comes to lighting an indoor garden. You need a minimum of 40 watts/sq.ft., but 60 watts/sq.ft. would be better. Either high pressure sodium lights or metal halide lights will help you to grow some large marijuana buds and are the most popular choices. For various reasons I recommend either a 600 watt light or a 1000 watt light. Mainly I recommend a larger light because people tend to over-populate a space and more is better to help prevent this. Also, this will be one of your largest expenses. A good HID for growing marijuana will cost you between $400 and $600 US dollars. During the ‘vegatative’ stage’ the marijuana will grow better under a metal halide, however, when it comes time to bud, high pressure sodium is the way to go! I recommend two rooms and two 1000watt HIDS. 1 Metal halide for vegatative and a high pressure sodium for budding if you can afford the space for the two rooms, the expense for the lights, etc.
Growing your own medicine is an exciting way to go organic! Remember to look for organic nutrients and such when growing as it is better for your health!