That's a nice looking boa.
Looking ahead, that boa (pictured) could easily live another 12-15 or more years because of the good care it's under. If the 8 year old boa you are looking at doesn't look as good as this one does, I'd pass.
You may also want to consider shipping and older, heavier snake will cost more than a younger snake.
I my personal opinion, there is nothing more stunning than a healthy, muscular, lean boa constrictor.
Any boa that resembles a blood python, is FAT and should be avoided.
All the fancy, morph colors in the world will not overshadow a healthy specimen.