The Large Mac's can easily live into their seventies. So, unless you are truly young, they will easily out live you. That provides good reason to consider a Rescue, especially if you allow the Parrot to choose you! IMHO, it is not a great idea to define your next Parrot to a single species as a large Mac that wants to be with you is much better than getting a Green-Winged that has little interest.
Start with your existing Avian Medical Professional as they know what Large Mac's are looking for a home in your area. Local Parrot Group(s) are also a great source as are the Rescues in your area. Breeders run the full gamut from poor too excellent. The Great Breeder will only sell fully fledged (a baby that is flying), where as a Good Breeder will only sell a fully weened baby that has been on solid food for two - three weeks. Anyone that will sell you a baby prior to above should be avoided at all costs.