not too sure i had my dad do mine for free hehe. got them smoothed as well.
Buy a set of second hand bumpers from a factory colour coded model, better chance of the paint sticking and lasting longer, than primering the black plastic ones he said.
Have a look in the yellow pages and find a bodyshop near you and give em a call and ask how much to paint two bumpers
edit: oops just noticed youve already had a quote. could probably get it lower. just shop around, and ask to see samples of work.
Where about are you from? local people might be able to reccomend somewhere good.