First, let me pay tribute to the CFL haters out there....
I KNOW HPS lights provide for potentially better results!
However.....you can find MANY growers who are using CFLs and getting GREAT results. If your budget and resources are limited, it's a great way to get started - you have less of a heat issue to worry about, plus you don't face having to rush out to find another bulb when yours finally does die. CFLs can be found everywhere - Wal Mart, Home Depot, Menards......
Do yourself a favor and research it a little, especially if you're only growing for your personal MMJ use.