About $300-$500 according to the estimator below. Almost all of that is the cost of the alternator.
Because the labor is so low the job must be easy and you may have a friend who can replace the alternator if you don't have the facilities. In that case you can get an alternator from a wrecking yard, which would be better than buying a rebuilt alternator (terrible reputations for reliability) and less expensive than a new OEM alternator. It looks like the going price for an alternator for your car is $125 at many wrecking yards... the second source will let you search many of the yards in your area. It is not all-inclusive so call around if you are going to go that route.
repairpal.com