I agree. There are always things you don't think about. In the winter I ended up getting two humidifiers and an extra light. Her first setup cost me $500 CDN (including my cham) and the second was about $500. I built it, but I made it just how I wanted (stained and varnished the wood, made it HUGE, added shelves, etc) I would go to the store where you are going to get the supplies and find out exactly how much you are going to have to spend. A cage is more than just wood... you need the wood, sealer, supports for the bottom, screen, maybe even another layer of screen (I use one for mycham toclimb in that's 1/4" plastic, and one to keep crix in that's charcoal metal screen - the screens alone cost me close to $75), nails, hinges, and something to hold the door closed. YOu can go a lot of ways with it. There are lots of cheap things you can use instead of expensive ones, but you have to think about if they can rust, and if you like how they look. If you don't care (and that's ok, a lot do'nt, im a girl, lol) than it will cost less.
After the cage itself you need plants. You can get a price on these at a store as well. Fake ones cost as much as real, and real are better, so you might as well get those. You'll want one big tree type thing (about 3' tall) for the main middle part, and lots of crawly things (like pothos) to help keep humidity in. Then there is the mister. And the lights (I spent about $200 on lights for the set up i have now). And the humdifier. Then you want about $200 set aside in case you need something more (lights, humidifier, mister breaks, etc - especially emergency vet visits). Then you need something to keep the crix and whatever else you feed your cham in. And their food. And their water. And mineral dust. Lol the list goes on and on and on...
All in all I spent WAY more on Orion than i thought... but she is worth it! I've had her about 6-7 months and have spent about $1500-2000 CDN. But, she is in her final cage, so now it's just food and vet bills, and bulb replacements, etc. And i have a tall lizzard aquarium that I like a lot to use for something else... I would list everything you want, and then find out exactly what it costs from the store you are going to get it, tax and all. That way you can be most prepared, and maybe even find some less expensive ways to do it!
~Lindsay