Have you tried contacting an independent locksmith? A lot of the locksmiths have gone high tech and have the ability to reprogram chipped keys for any type of car. You would be surprised to see the type of equipment that they have tucked away in their cargo vans. Just a thought, I never believe anything that a car dealership has to tell me. Having to replace a ECM in order to replace a key seems sketchy.
Alex Lock and Key?