Actually, MLU is most appropriate for a fairly narrow range of shutter speeds - roughly .25 sec to 1 sec. Faster or slower than that and the vibration induced by the mirror bounce is not much of an impact.
My advice is go with what you can afford and use a remote release, or if your camera can do a delay, use that. At the speeds where MLU is effective, the other major contributer (IMHO even more of a problem than mirror slap) is the vibration induced by pressing the shutter, a delay or cable release will deal with that.