Good for you! Let us know what parts you are going to choose. Keep this in mind: Never go cheap on the power supply otherwise you'll have headaches and with a few exceptions power supplies that come with a case are garbage.
You can get some great deals from Amazon but I also want to direct you to Newegg.com. Its a great place for computer parts. I, like many, have used them for years. Also, if you are fortunate enough to have a Microcenter near you -- GO!
Corsair makes really good power supplies. Others do as well.