A reptarium is fine. You should buy one that is no smaller than 3 inches snout to vent length. The most important things to consider when starting out with a juvenile veiled chameleon are 1)basking, 2)uv lighting, 3) water, 4)food. (don't forget plants and appropriate sized perches)
1> for a basking light I would recommend a 50 watt spot light kept a couple inches from the reptarium and a branch that is in the reptarium approximately 5 inches from the bulb.(keep the room between 70 and 80F)
2> the only effective fluorescent bulb is the zoomed reptisun 5.0 bulb(Ferguson et al.). Which should be kept directly on top of the reptarium(only good for about 10-11inches). Another effective bulb are one of the self-balasted mercury vapor bulbs ( these are much more expensive though).
3> you need to drip on your chameleon and mist down the plants in his cage at least once a day. You can create a simple drip system by taking a large plastic cup (32 oz work well) and poking a hole in it with a thumb tack. You can fill this up with water (make sure it is between 65-80F) each morning and set it directly on top of the cage. You can put a plastic dish on the bottom of the cage to collect the falling water.
4> keep a container (deli cup, small cup, etc.) to put food in. Crickets should be the staple of the chameleons diet, order crickets online(you can get crickets for one tenth the cost pet stores sell them at) and keep them in a five gallon bucket (or some similar container) with kale, carrots, and a high quality cricket food. you should dust with multi-vitamins and calcium every other feeding for the first couple months and then every third feeding when about 5-6 inches snout to vent length. Veiled should also be feed vegatable matter, the easiest is to feed dandelions(make sure they are from a place no pesticedes were used) which seem to be a favorite and the chameleon will eat immediately. Also feed mealworms once or twice a week and waxworms every couple weeks.
You should be successful with these tips.
vadoni