Cured rocks are more expensive, but personally I think it is really cool to see all the life come out of your rocks. You will still have to cycle the rocks, but instead of having just rock you have all kinds of cool stuff. On my 25 gallon tank, I bought 25 lbs of live rock and had a crab, clam, snail, spaghetti worms, bristle worms, etc. It gives you something to look at and enjoy until the tank cycles and you can get fish. I recommend cured rock if the cash difference isn't as much of an issue!!