To respray the entire bumper, you're looking at 500-700 to do it right. I'm sure you can get it done cheaper if you shop around, but beware of quality if that matters to you. Spot painting can be done for less, but make sure you use someone who knows what they are doing.
I've received great results from Haury's Lake City Collision in - you guessed it - Lake City. They also offer a CCA discount, if you are a member.
2012 328xi Touring M-Sport