I think the first one is free, the addiitonal ones may be more.
But, it is not real $9.25 per card, it is $9.25 - $2.50 = $6.75 per card, since you are getting $2.50 back for your equipment.
Why do you need 3 CableCards? Each card is capable of decrypting 6 streams at once. Get a device that utilizes CableCard's full potential.
We rent 1 CableCard and it serves 5 TV's. All function independantly from each other.
6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!