I do not know much about iguanas so I am only coming to offer advice on buying cages- I would try and build one yourself. I did a quick google ass im only familiar with making rodent cages (I'm on the train on my iPhone so can't do much sorry) but it seems like there are a lot of resources on different ways to go about it. It won't be dirt cheap but there are certainly ways to make sturdy cages that are relatively inexpensive and functional even if they aren't particularly pretty (although I see some people working with wood and making beautiful enclosures if you have the money and skill/handy friends)
![Smile :)](https://mlparena.com/Smileys/default/smile_001.gif)
however I am not sure since he is so young what an ideal young iguana enclosure would be. I have seen people make enclosures for young reptiles etc out of large storage bins, cutting out the sides and cover and replacing with hardware cloth. I would see if that could be an option?
Again I wouldn't take any of my advice straight without doing further research but maybe it's something to look into?