About how much would it cost to change a timing belt on a madza 6 i would like to change it before it breaks.?

its easy to do yourself, get the book and you will see, probably a feww hundred bucks,, thousands if it breaks,, go to askmyautomechanic.com these guys are greatAbout how much would it cost to change a timing belt on a madza 6 i would like to change it before it breaks.?
I dont know why you would change something that works unless you have too much money on your hands.About how much would it cost to change a timing belt on a madza 6 i would like to change it before it breaks.?
WHATS YEAR AND ENG SIZE I THINK IT HAS A CHAIN NOT A BELT
i have a 4cyl 2.2L motor and i put one on every 80,000 miles