I don't think there is any problem in buying a mix breed panther. If you have no plans on breeding it and just want a pet then I don't think it matters. Also who's to say panthers of different locales never mate in the wild?
As long as the breeder is telling you that it is a cross breed and not trying to con you by saying it's a pure Sambava when it isn't. A half breed panther can look great, I've seen some that knock the socks off pure strains. It's not inbred so there's no worries about the dangers that poses.
As far as pricing goes $160 doesn't seem "too" cheap to me. Some of these places buy their stock in large quantities and can therefore sell at a better price, like Sam's Club.
I do agree that the locales should be preserved as best as possible, and that every breeder shouldn't be producing mutts. Though a few cross breeds aren't going to ruin all the bloodlines, and if they are just going to be kept as pet's then I don't see the harm.
I'm sure people will disagree but like I said before you are going to have cross breeding and even some inbreeding in the wild. A male Sambava isn't going to ask for I.D. when it comes across a female, it's just going to have at it. You know how boys are. 