I agree wholeheartedly that there are AdWords experts, formulas that can be used, secret sauce that can be leveraged, etc.
I also support AdWords vendors and their practice and I think their pricing is actually quite fair typically.
That said, some of the best campaigns I've seen came from the guy who works at the dealership and offered to fill a void.
He puts his heart, the store brand and everything he's got into making the campaign work and ensure it matches what they do in store.
I see huge success when people do this. They know their customers, they know their target audience and they know the dealership.
AdWords isn't so complicated that it requires expertise - it's more of an icing on the cake.
I've seen employees go from never touching AdWords to having one of the highest ROI campaigns in less than 60 days.