Cages can be rather easily constructed from window screen framing (cut to size), they sell L end pieces (avoiding miter cuts), rubber splines, and screening. Build each side and attach with small screws. Hardware can be bought for the doors.
A couple of things about screening.
Fiberglass constructed screening looks great. Over time it will shred apart and can become londged in feet and toes of chameleons. Bugs can chew through fiberglass rather easily.
Aluminum screening is better but still has big problems. It is hard and can trap large (adult) chameleon toe nails. When they try to dislodge them they can break off. This can lead to complication depending on how it breaks. Insects could get through this but it is very unlikely. This can be used on juvinilles with no worries. Their nails are not big enough. I have found this before in a coated variety before and it would be pretty safe. You can use this with adults but hole sizing is crucial.
Polyester coated with vinly. It is a little darker as far a visibility goes. It comes with nice sized holes and is flexible. I have posted something on this semi recently and the point that it could be a fire hazard under a heat lamp was brought up. You could just use aluminum on the top it would be safe and light up the cage better for visibility. I could be chewed through.
These are the only ones available in my area. Pieces could be bought at Lowe's, Home Depot, and some peices at Walmart. A tub for motar could be bought for a bottom, with wood framing around to stabilize the tub, a hole cut in the bottom for drainage, a drain cover (with small holes), a bucket to catch water, and the screening part could just rest on top. You could also build around the frame to hide the bucket and give it more of a counter look. The bottom could be constructed from thin 1/8 pvc plastic and use paper towels to soak up the mess. I have seen some one use a dryer piece in here. Some people use real substrate and still isolate the plants from the rest of the substrate if matianance is required to the plant. A substrate recommendation is "ify" with a lot of people.
I personally like veileds. Panthers are not bad for beginners. There is a huge price differences. There are a couple links at the top of the home page with breeders.