Listen to Purplemuffin's advice. Sorry for the doom and gloom, but...
Iguanas are great, but they are a real challenge. Even if you ARE experienced with some of the easier lizards such as bearded dragons or leopard geckos, iguanas are in a completely different league.
Can you buy or grow fresh organic produce to feed it every day? Can you clip it's nails? Iguanas can scratch you up worse than any house cat, whip you with their tail (which will also scratch), and they can also bite. Not all of them are this aggressive (many CAN be quite sweet), however are you prepared to deal with the aggression? Oh one more thing, their poop is in a different league too!
"Petstore, craigslist" Sorry to be harsh, but are you serious? In my opinion these are the two worst places to buy any animal. Buy from a good reputable breeder.