There's the money you pay up front, and then there's the money you pay for vet bills because you have a sick pet. The best way to find a healthy animal is to find a reputable breeder. Contact a vet or a rescue center to see if they know someone in your area who can provide what you want.
If you use the Internet to find a pet, check the source very carefully. Try to find someone reputable who can verify the source as both legal and run by an expert in the pet you want to buy.