That would be good for a 3 month old Jackson's. I plan on free ranging so i dont want the screen to be too big so feeders can escape, but also big enough so if my cham climbs on it he shouldn't hurt a nail... (looking to buy one as i am not skilled anough to build one myself).
Reptariums are not a bad option. There are horror stories with them and claiming chameleon nails. I would not be to concerned with that just keep it in mind to whatch if it does happen. If you have plenty of climbing branches you will almost never see them on the walls anyway. Insects can chew through the mesh given enough time to do so. I have experienced this first hand but it was error on my part by overfeeding the chameleon what he could handle in a timely fashion. I have had the zipper problem but as long as you use both hand it completely elimanates it.
ESU makes some cool cages. I used them for the beginner cages. I have read of the hardware rusting. I have never had this problem although I only used them for a couple months at a time. I have not gotten specifics on which pieces rusted but a trip to Home Depot and some zinc coated steel would probaly do the trick. One thing I did not like about these cages was the drainage or lack of. You could put a hole through the bottom and drain the water into a bucket with probaly not alot of effort or know how.
I have seen a ton of people that sell cages they build online. Alot of these seem good but there a lot of problems with these to. Most I have seen use aluminum which is not good for chameleon feet I my a opion they are far worse then any reptarium. Again if given time an insect can chew threw aluminum or almost anything they try to. Both of these problems can be eliminated with proper husbandry.
There are pros and cons no matter which way you go. The bottom line is no matter what you go with you will have the biggest impact on your chameleons life. Your knowledge of the animal and ability to apply it in the enclousure.
I was just making a point about that insects could chew through anything. I am partial I guess to reptariums and I hear so many people trash them over that point. When really a determined insect can get through almost anything. I like those deluxe deals they look like a pretty good affordable option especially with everything you get. I have heard mixed answers as to the proper housing size for a adult Jackson male. The rule of thumb I like to go by is the width and depth should be 1 1/2 their body length. At a max size of 14" I would try and go with the 24"x24"x36" for an adult. With proper supervision I would think you could use this size from the start as long as we are talking about a fair size subject.
IMO.. the best cages on the market are the ones built by cages.net that use the coated 8 mesh. The only thing left to work on with this cage is the drainage. There is a person on this list who had one special made without a bottom on it so that he could mount it on a cement mixing tub that had a drain built into it. Perfect solution.
Cricket chewing is NOT a huge deal. Overfeeding, not leaving a bit of food in the cage for the crickets, and leaving feeders in the cage overnight causes this. It takes them a while. The first cricket container I made had fiberglass screen over the ventilation holes. Not the most brilliant choice, but it was fine until a chick waterer (the tray stuffed with cotton) fell over and flooded the container. For months prior to that, they were fine.. fed well, temps good, water.. and didn't chew through the screen. It wasn't until they were soaked that they became determined to get out of the box. And, a piece of thread and a needle fix any holes up very nicely.
Galvanized steel mesh is dangerous in that it can be sharp and cut your chameleon's feet. The coating on galvanized steel mesh is thick because it is dipped instead of electroplated. This means more zinc that your animal will be exposed to. The galvanized coating rusts white rust from the zinc. The rust is toxic if ingested. It would take quite a bit to be lethal, but if your cham shot at an insect and came back with a glob of galvanizing, it is possible it would poison your cham immediately. Research in birds shows that the zinc in galvanizing builds up in their organs, leading to a chronic toxicity level. I don't believe that any research has been done on it regarding reptiles. If you really want to use galvanized steel mesh for your cage, you should clean it with a scrub brush and vinegar solution to remove the rust on a fairly frequent basis. IMO.. it isn't worth it.