If you go the ISF route, make absolutely sure you get someone who knows what they are doing. Lot of these guys running around who do not really understand the fundamentals of color, the frontend processing of digital TVs, or proper use of calibration equipment. You will also need to make sure that the calibrator has the factory codes to unveil the factory adjustments for your TV and more importantly, understands what they do (this is rare).
Getting a cheap Avia DVD and running the straightforward tests on it will do 95% of what an ISF calibrator will do for a fraction of the cost. I develop TVs for a living and know what ISF calibrators do. Safe to say they are usually not worth the expense.