What is a good Shampoo which doesn't have sulfate in it?

After some research I think that the sulfate in my shampoo is irritating my scalp? I would like a good shampoo that doesn't have sulfate in it to try out and see if my scalp clears up. I have tried Aveda products, and I loved it! It's a bit on the pricey side, so I would prefer to hear some slightly more affordable options!