He eats pretty well, all the right things (wont eat in front of me or from my hands...)
That's fine and normal. Eventually he'll get used to you enough to eat in front of you. Hand-feeding can turn into a habit, so don't work on it.
I am either going to buy this cage (the giant one) which is 42 X 31 X 55H for him for the next year or two OR start working on building one.
That will work for a year... minimally. By the end of this year, get ready to give it a full-size condo. Juvies grow fast, and iguanas need LOTS of room to excercise and move about.
Length and Height are the two most important measurements, and depth can be somewhat compromised. Minimal length and height are 6 feet both. I'm talking minimal. Ideally, over 7 feet, with 8 and over being the truly best. Think about it: a young iguana is 2.5 to 3.5 feet long. Therefore, ideally it needs an enclosure twice its length up and forward, and at least half of its size (the iguana) to turn around inside. Therefore, a young iguana needs a minimum of 6 or 7 feet high and long, and about 4 feet deep.
Bigger is better. You wouldn't like to live in tight quarters, and neither would a wild animal evolved for open lush forests.
$150 is not bad at all for the Giant cage, but keep in mind it's a short-term investment. Save your cash and start making plans for a BIG enclosure ready for the new year. Custom-built enclosures are often the best way to go. You can get plans and ideas from retailers and other cages you can google online.
Important things:
1) it has to be big
2) it has to be safe: for your home (fire hazards) and your ig.
3) it has to be easy to clean. Enclosures should always be cleaned daily.
4) it has to be functional: provides basking spot(s), cooling area, hiding spot(s), feeding spot, water, climbing areas, able to keep warm but also ventilated enough to avid cooking the animal. It sounds harder than it actually is.
5) it has to look natural. Exotic pets rely on wild-life stimuli reproduced in a captive environment to stay healthy.
6) keep it fun. Have fun building it, take your time (hence why it is good to start a month or two earlier), do your research, be creative, and enjoy.
Iguanas are remarkable escape artists. At roughly 2 feet in length, he may be able to get through... and if not, he could get stuck! Measure his girth at the fattest area of his body, and the girth of his head. Keep in mind lizards deflate to sneak thru tight quarters.
I can't see the picture, but sounds like you're doing ok!
-IJ