How much would it cost me to get new timing belt fitted at garage on a ford fiesta ghia 1.8 diesel p reg?

how many miles should it be changedHow much would it cost me to get new timing belt fitted at garage on a ford fiesta ghia 1.8 diesel p reg?those usually cost about 100 bucks with parts labor and everything,there not that hard to replace,and it doesn't take that long to do this job,good luck with it.