Best bang for the buck 12.5" nitride barrel?

[MichiganMitten]

I'm looking to do my first build with a fellow vet, who will help me out. He is trying to convince me to go 10.5" blackout (he runs subsonic & suppressed). But everything I've read points to the 6.5 Grendel being a superior platform for supersonic performance.

With that being said, I don't know where I can get a quality and accurate barrel at a good price. I called Mark @ Precision Firearms, and he said that a completed 12.5" upper would be ~$500. With an additional $50 and 8 weeks for nitride treatment.

Any alternatives out there?

Thanks for any additional advice for a newbie.