My very first chameleon was a WC Jackson's I got at a reptile show, I just made sure to buy one that had:
- Bright, alert eyes. Not sunken.
- Good body weight
- No scratches, injuries, breaks, or off-looking skin.
- Up and walking around the cage
Etc. Just your usual healthy cham attributes. And the little guy I picked was awesome, and didn't give me any issues for the years I had him.
Jackson's don't belong on Hawaii so you aren't removing valuable individuals from a failing, indigenous population as with other species. You still have to let them adapt to captivity like anyone else, but it's not as morally troubling as exporting endangered or near-threatened species from the wild.