For that price, I would hope it's cured. Uncured live rock will smell bad as Lazy said. Look to see if there's signs of death on the rock as well (brown algae or slime). If the rocks are brightly colored and have lots of life on them...it's a good price. If you're looking for inexpensive rock, I would just buy some lace rock...and seed it with a rock from someone else's tank.