My bad in assuming service life. Initially when I read it I had it correct then let myself believe service life... Go Figure!
OK, let's look at what CMP says about the special grade rifles:
The problem I see is there are only so many of certain parts out there to be had. While aftermarket parts like stocks, hand guards, and even barrels are easy to come by many of the currently parts that are being refinished are not commercially available. For example parts like the operating rod or gas tube (I don't know of any aftermarket gas tubes) as well as many of the small parts like the bullet guide and like parts. Years ago (as little as 15 years ago) these parts were abundant and relatively inexpensive, they are slowly going away. They also have increased considerably in cost.
How long some of the marketed CMP variations will last is anyone's guess. One poster seeming in the know says based on their current sales they will have some rifle packages for another 3 years. I really don't know.
I have a few including an unusual match rifle actually chambered in 7mm-08 which is an odd Garand. I also have a good supply of parts to last me. If a private sale came my way for a good price I would likely grab it.
How long you wait is up to you. Life generally deals out other priorities over buying a new gun. If you have not done so already I suggest you borrow one if possible and shoot it. As I mentioned in an earlier post I have seen people buy an M1 Garand only to find out hindsight they really didn't care for the rifle.
Ron