Nice! I've been wanting to get a 308 as well. I was looking at Rock River Arms this morning. They have what they call the X-Series with an 18" barrel. Just a matter of when I can pull the trigger, so to speak...
I've built 7 AR's over the years, so yes building an AR10 is something I've thought about. I might do it.Have you considered building one? They are quite easy to assemble with just a few tools.
That way, you can slowly acquire the parts you like w/o spending a lot of money at one time.