What is the cost of replacing ignition coil?

You can use a volt meter to check the resistance of the ignition coil against the others. I bought my Delphi ignition coils on Amazon.com for about $67 each. They are very easy to replace. All you have to do is remove the engine cover, unsnap the wire from the back of the coil, then undo the bolt for the coil and pull out the coil. Easy peasy.