I have heard that it cost up wards of 500 dollars to have my oil changed and to get all the fluid levels checked and to get just a basic check up at a Harley Dealership, is this true?
Now is this original miles - 15,000 on a 1999? If so that is really low mileage.
Many riders do not realize that even if a bike is not ridden many miles in a year, some things should be done based on time not just miles. This is especially true of fluid changes, but some other things suffer from the ravages of time too. Check the condition of hoses, tires, drive belt, brake calipers and mating surfaces when you first start the bike to make sure that any unseen orings or gaskets have not developed leaks.
So as a rule of thumb, your fluids should probably be changed annually (definitely engine oil and brake fluid anyway), and all "rubber" items inspected for condition.