Yikes.

Things I would look at in purchasing an animal of any species:

Is the breeder taking responsible and ethical care of the animals, keeping them apropriately and humanely, and breeding for the love of it, not just the paycheck?

Are they from healthy stock, and likely to stay healthy, or inbred and weak due to for-profit breeding?

Do you have a vet experienced in the care of the species?

Are you able to provide adequate care, socialization, and housing for the adult animal?

If you are iffy on any of the above, especially with animals as frequently abused, neglected, and turned over to rescue, I'd steer clear. Big cats are a huge challenge and responsibility; there are no minor problems and a bad event can result in their death, if not harm to a person. Are you willing and able to take responsibility for that?