As mentioned the starter sounds like it's not engaging the flywheel properly, expect to pay anywhere from $100-300 for a new or rebuilt starter. they are usually not to bad to change out, depends on the car, the minimum you will need is a jack, jack-stands, socket set, box-wrench set, possibly some pliers and screwdrivers to remove plastic engine covers that may be needed to be removed. If you plan on DIY auto repair buy a manual for your vehicle from either Hayne's or Chiltons. They are far from perfect but for the $11 you will get something that will show you step by step how to change out stuff and what tools will be needed. Also when posting a problem in the Garage forum it's helpful to list the make, model, year, engine of your car as their is a fair chance someone else might have experience with that model of car and have worked on one.