Gracefuls and Senegals are often very difficult in captivity. They go through a lot during the import/export process. Many of them die and the ones that survive that often die from kidney failure at a later date (like once you own them) due to no water during the importation proccess. These two species of Chams are 2 to avoid. They are basically regarded as expendable by nearly everybody along the import/export/pet shop line. They are all wild caught as breeding them is very difficult and there is no money in it. This is sad but true.
Imported Panthers fall into a different category many breeders will buy a wild caught panther because it provides them with a new bloodline. I think all importations of wild animals are difficult but the importers for Panthers will take the extra precautions to insure the animals arrive safely. Breeders will pay top dollar for a Panther in good shape, Madagascar importers like Olaf Pronk know this, thats why they are a lot more expensive.
I would check the kingsnake.com classifieds under chameleons. Lots of the people doing business on there will ship worldwide. Find a few people like that and e-mail them. Most of them will be involved in the high end top dollar type chams but maybe one or two can get you a Veiled or other cham suitable for a beginner.
Please stay away from the Senegals, Gracefuls and Flapnecks. If there is no demand for them, they might eventaully stop importing them. This would end some real atrosities done to these wonderful little chams that usually don't fare well in ccaptivity. The initial cheap price is often made up in expensive vet bills later. Good luck.