Wow, there is a lot of misinformation in this thread...
C. parsonii are expensive for a combination of reasons. First, this species is simply a spectacular animal. They are large, majestic, colorful animals with unique skin, intelligence and personalities. They have the potential to live long lives (although rarely do in captivity due to poor husbandry). They are saught after animals in general and as a result have high demand. Secondly, this species is quite rare in captivity which creates high demand and obviously low supply as well.
They are rare in captivity for a number of reasons. First, in 1995, CITES recommended that their export from Madagascar be banned. All CITES party countries are legally bound to these CITES recommendations. No legal C. parsonii have left Madagascar since that time. Next, despite some people claiming that this species is not difficult to keep in captivity, their dietary, water and temperature requirements have resulting in few keepers successfully keeping this species long term. Most of the animals that were imported prior to the ban quickly died off and very very few reproduced. Additionally, this species is very difficult to breed. Getting a pair to breed is extremely different from other species (a child can get Veileds or Panthers to breed with little effort) and is extremely rare. Females have had notorious egg binding issues despite the best of care, nutrition and experience resulting in numerous fatalities. Finally, the eggs take 16-24 months to incubate and most of the eggs die before hatching. Then, if a breeder is able to get to this point, they encounter the typical issues of raising baby chameleons.
C. parsonii have only been bred to F2 a handful of times but not to F3. WC C. parsonii are completely illegal. Imported babies from breeding farms in Asia, which many people question, are available but these have captive bred CITES documents. Any C. parsonii that is WC and not exported from Madagascar before 1995 is illegal, period.
Chris