Well, i too have had that experience. I was looking for a pet when i was in the tenth grade ad was told that an iguana would live for a couple years and that a ten gallon tank would be good lol. Hundreds of dollars later my 5 year old iguana is in a 7 foot enclosure in my living room. Needless to say i have never had another impulse buy again, even though i did end up with a really amazing pet. There is actually a lot of overlap between iguanas and chameleons. They are both aboreal and have similar husbandry requirements, although chameleons need more fresh air and iguanas of course would eat every plant in sight rather than perch on them.
The biggest problem i have though would be that i am a current college student, and i would have to transport my chameleon once in a while. I have read that it is ok as long as they have a month or so in between transporting. Does anyone have an opinion one way or the other?