Actually the mixed greens salad worked well. Tops of carrots, spinache and kale are the best. Dandelions as well. What I did is make friends with the produce guy in our store at the time and any time something was getting too wilted to sell, he would give it to me. This is a website that tells you how much of each but we just winged it. We fed him more lettuce than they suggest but he was healthy. Most fruits and veggies are fine but certain ones should be staples like okra, watercress, and snap peas. The best thing is not to pay for your greens. If you know someone at the store, fruit stand, or restaurant you can get veggies for your iguana.
Hope that helped, the site was really cool.