$300 doesn't seem to far fetched for panthers. I've seen them from about $250~$400.
He's beautiful !
The local reptile shows were the $250 panthers:
I also was like you and thought "why so expensive"??

When I couldn't get them for any less than $300 from a reputable breeder, I looked much more closely at what I was getting for the money as opposed to the cheaper $250 from the reptile show. What I learned is that the shows (unless you go to the larger ones and then you are paying the $300+ price anyways) are usually middlemen of smaller breeders who do not necessarily specialize in chameleons. I would have a hard time getting assistance from them later as they all seemed to have bought from a larger breeder and they new little to nothing about the animals other than the basics that anyone can look up on a forum. With so little knowledge of the animals, I had to question the health and quality of the animal. He was a cutie though...
I paid over $300 for mine from a forum sponsor and breeder. I couldn't be happier. The assistance and knowledge shared are worth the extra cost. I look at it like a sort of insurance policy. I feel confident that my little Cham is healthy, comes from good breeding and if I have any issues, I can always email Nick for help and he was very responsive to all my questions and concerns. You can't get that level of help from a cheap fly by night breeder.
Sherman: my beautiful little boy panther from Canvas Chameleons.