A lighting store, if you have one nearby. Seriously.
Remember, lighting is like furniture. NO PRICE is ever final. Always see if they can do any better.
Then there is Lowes and H-D. But most of what they sell is crap. Most, not all.
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.
Answers based on the 2008 & 2011 NEC.