You have to decide how much value they are offering your business. If you have the time I suggest you study the Google Adwords Learning Center http://www.google.com/adwords/learningcenter/ .
Remember you are the expert in your field and you should play a significant role in the campaigns development. The PPC expert should help you understand the nuisances of the Adwords platform, avoid pitfalls and stay abreast of any changes in Adwords.
You should also demand transparency from whoever you work with. |