The cost of an ISF certification at Best Buy is $300; but, they discount the TV by $100, if the service is purchased along with it.*
This service also includes a Home Theater calibration if being used in the same room as the calibrated TV.
There are certain brands of TVs (ie; Sharp and Dell) that cannot be ISF calibrated, and might benefit from the Spyder service.
To my knowledge, the only thing you get with a FireDog calibration, is a guy in a green shirt who will do the same thing you can for $125 more.
* based upon a TV costing $999 or more.