How much would it cost (approx) to feed and look after a labrador each month?

Okay, I have a lab and he is CRAZY!!! They need lots of time spent with people, they love to please and just to spend time playing fetch or going to the beach... They are very easy to train they are quite the smart dogs! They need space to run and man do they love to run! It is absolutely necessary to train them a reliable recall because they get distracted with smells, noises , etc. Well we buy a separate kind of dog food for our lab because of his hip problems and a high quality dog food costs us about $45 and lasts us about a month 1/2 for a 30 lb. bag. Tell your friends they'd better think things threw before actually taking on TWO (?!?) labs.