I've got a barrel on my 300 blackout now that just plain won't shoot tight groups.

I have a noveske 556 barrel thats 10.5" that's sub-MOA with the right optics and trigger and me doing my part.

I want to buy a 8.5-9" 1-7 or 1-8 twist 300 blackout barrel that's fairly accurate, but I'm just not willing to pay Noveske prices again.

Any ideas?

What ammo are you using?  MOA at what distance?

300 Blk isn't exactly what I would consider a "precision" round...

I would talk to the guys as Ballistic Advantage to see what they might have for you, or what they might think about a shot barrel with that type of performance.

Im using handloads with half a dozen different powder and bullet combinations, as well as factory ammo and it still wont hold tight groups.

Also, theres inherent in the cartridge that says it cant be capable of the same accuracy as any other chambering...

Sure there is.  You have to remember that most of the 300 blk loadings are using bullets that were designed for bigger .30 cal rifle cartridges like .308, .30-06, etc.  This is a nice selling point of the blackout because it uses commonly available bullets, but those bullets were designed to be fired are much faster speeds out of those rifle cartridges, their shape and balance is tuned for that, as well as the common twist rates of those chamberings.  Firing those same bullets out of the smaller case with faster powder and usually faster twist rates in the blackout may not achieve the same level of stabilization, and precision will suffer.

.300 Blk is nice because it is easy to reload (using modified common .223 cases and readily available .30cal bullets) and can be loaded subsonic for use suppressed while all fitting in the AR15 platform.  High precision is not one of the cartridges strong points.  Can it be done, sure, but it's more up to luck or getting the perfect load for your barrel.

https://www.ar15.com/forums/t_3_121/691668_Any__300_Blackout_Ammo_Actually_Shoot_Sub_MOA_.html

http://rifleshooter.com/2016/08/300-blk-accuracy-maybe-it-isnt-you/

Ballistic Advantage or Faxon.

I have a 10" Ballistic Advantage that makes 5 shot groups with all shots touching each other making one jagged hole using a 3moa red dot at 50 yards. I'm sure it can do better with better optics.