To answer a previous question, the modification costs $45.
It's worth pointing out, for the sake of clarity, that this modification essentially allows the taking of a picture to be split into two separate actions:
1) press the shutter release: the mirror flips (and stays) up.
2) press the shutter release again: the shutter opens & closes, and the mirror swings down to it's locked position.
It does significantly reduce what appears to be the bulk of the vibration, which is induced by the mirror hitting the bumper on the upswing. This mod is a boon to those of us who find ourselves shooting static scenes in low light on a regular basis, but requires a fair amount of practice (which i still need) for more action-packed scenarios.