I almost bought a laser bore sight once. I don't know why, but I was shopping for some things, and had a rifle to sight in at the time, and I thought, "hey, I should get a laser bore sight."
I started looking at them and then I suddenly thought, "these things are $50-$80+ and looking through the bore has gotten me through sighting every rifle so far." So I didn't get one.
I might consider one if I was swapping scopes around a lot and sighting in rifles frequently. For the most part I don't see them being worth it for the few shots it might save every now and then when I sight in a rifle.
Plus, maybe I'm just paranoid, but clamping a metal rod into the muzzle doesn't strike my fancy.