The tune on my Cobra cost $300 from the best tuning shop in my area for Fords. I did have to purchase a tuner before that which was $379 so overall spent around $700.00 for a tune on my car.
To me...I'd rather pay more up front to have it done right the first time. Ask around and find a shop that has tuned a car with a setup close to yours, or is known for having spot on tunes, and use them.