I think your assumption is way off.
Welcome to the free market where supply and demand sort out the price.
If panthers were actually over-produced and over-priced like you say, the breeders would be stuck with animals they needed to get rid of and soon the price would drop. It happens with every other lizard- panther chameleons are sold in the same market place as the rest.
Your assumption that price is set based on some percentage of production cost to come up with a profit margin is only partly true. Look at the operating system most computers use- windows. Bill gates is a billionaire many times over. Think that is because products are priced according to the cost of production? Think again- demand plays a big role and demand is created by perception. Windows generally sucks most releases (xp and 7 being the exceptions with all the others mainly sucking big time) but because it won the business market early on, it was perceived as the best and demand allowed it to be priced very high compared to production cost. Price in a free-market is based much on perception which creates a demand. Production cost and difficulty is only the first step in determining price.
Veileds are in fact lots easier to produce in large numbers, especially if the long-term health of the mother is not a consideration. Plus they are lots easier to go many generations without investing in fresh wild caught bloodlines.
Plus as someone who was away from panthers for several years, they did in fact drop in price while I was gone. I remember them being around $300-400 from just about anybody. Now bargain shoppers can find lesser known breeders and get them for $125 or less.
Haha I have found you can get high quality chameleons from just a regular joe that has a breeding pair.
I have found that "regular joes" are sometimes great places to buy lizards and other times a bad idea.
An awful lot of bedroom breeders bought brother/sister pairs of lizards at the nearest reptile-show from other bedroom breeders who did the same before them. An awful lot cut their weaklings out of the eggs so they can survive to be sold. An awful lot breed a few clutches and then because of poor husbandry fail to repeat their success and get out of it. The risk of bargain buying accidentally mixed locals is higher also because the bargain bedroom breeder often only has a few lizards to judge whether that female they got is mixed or pure and they don't keep things back long enough after hatching to verify. I've seen about a "zillion" bedroom breeders come and go on various lizards and many of them don't even last a year.
On the other hand, sometimes bedroom breeders are in fact a very good source of quality lizards. They often do not have the need to make an actual profit on their animals, so if they have sufficient means they can invest more in the care of their animals and sell them for less just because they are in it for fun and don't need to worry about the bottom line (or maybe have an incorrect idea of where the bottom line is because they forget to add up some of their investment when producing the babies like costs of electricity, medication for the parents, housing, light fixtures, supplementation, insects, labor-time, etc).
So yes, sometimes bargains can be found and they are worth it. Other times it can be a gamble. The trick is to figure out which is which. Other times the buyer is in fact paying for the breeder's name, but often that name is worth it. Plunk your money down with the kammers or screameleons and you can rest easy that you have a nice healthy very well started lizard on the way that is going to thrive for you without a lot of fuss at the start. Sometimes that peace of mind and feeling of satisfaction and quality is worth the extra cost.
Sometimes you really do get what you pay for.
As for the cost of the not-so common species- I agree with you in that most are dramatically under-priced. I've put a bit of thought into this in the past and have come up with some valid reasons.
1) All of these cheap species are available very cheaply as wild caught. Sometimes in large numbers. Like it or not, import price effects the marketplace price for captive bred individuals.
2)Cheap imports also negatively effect perception of certain species. The perception is cheap=junk (and often it does- imports often crash and die within weeks of purchase).
3) Big breeders don't work with the other species because they are a bit more difficult sometimes to get figured out and going and then they are cheaper once they do get going. It's a circle where panthers are selected because they are a sure thing, and their price makes the investment worthwhile.
4)Advertising- panther chameleons are advertised all over the place as "the" chameleon to get. Magazines, books, the internet- all advertise this idea. Veileds are the cheap introduction, panthers are what you really want when you can afford it or are the goal to achieve after success with veileds.
No magazine article says dilepis is "the" hot new chameleon to get. Indeed most magazine articles on chameleons only include veileds and panthers and maybe jacksons if jacksons are lucky.
I really admire the guys working with the kinyongia species. They are building a market for this species and slowly getting people to recognise what wonderful animals they are. What they need next is an article in REPTILES magazine.
Just my random thoughts on your topic.