Dead Live Rock Mixed with Live Rock

[gobytron]

That's a good way to go.
Your initial cycle might take a little longer than it would if you used all new live rock but you have a larger measure of control if you use dry/dead stff since you have a better undertsanding of where it's been.

There are also no guarantees that just because you buy wet rock from a lfs that is is aywhere near fully cured or fully cycled.