Did you get anywhere with this? I have been looking at 'air-layering' to grow roots on an existing branch. That gives a useful sized plant to grow on. Where did you get the 70 years from? The bumpf I've been reading shows plants starting to crop at 5 years and good yields at 12 years.
I've noticed a lot of Catalans planting new little carobs around us, don't know where they get the plants from.
We also have some baby trees growing under out old carobs. We ill transplant some of those if and when we ever get some rain. 

It takes seventy years to get to maturity. That has nothing to do with cropping. And no I didn't find anywhere selling them and received no suggestions. I intend relocating some of my younger trees but I was hoping to get a 5 or more years head start. And surely ALL trees you plant will be an inheritance?
Bruixot