Do you think you'd save any money? I don't know how hard it is to fit a barrel, but two posts here refer to gunsmiths who will do the job for $500. Wouldn't much labor to add up to $150.
I also wonder if it's harder to fit an octagonal barrel. Not only does the barrel have to torqued, etc., but the top of the octagonal barrel has to be flat - if it was screwed in a little too far, or not quite far enough, then the top of the barrel would be cockeyed, and that would look pretty funny.
Mike