Unless you have an abnormally small BP mouse fuzzies are most likely too small for your BP. Right out of the egg BP's are big enough to eat either hopper mice or rat pups. Basically you want to get a prey item that is roughly the same size or slightly bigger in diameter as the widest part of your snake's body. Offering you BP a weekly meal sounds just right. You can't overfeed a Ball Python, believe me if they are not hungry they will NOT eat.
As TheWinWizard said you can look to see if there is a herp club or warehouse mousery in your area were the rodents are MUCH cheaper than petstores.
If you have a hard time finding a local herp club or mousery I would recommend checking out a local reptile expo. There they usually have people from that area selling rodents who you can likely get a custom order from. Also reptile expos are just awesome events to attend in general.
You can see a good list of upcoming expos nationwide at: http://www.kingsnake.com/events.php