Does anyone make a 'medium priced' 6mm ARC Complete Upper ?

Hello Guys, I'm thinking about picking up a Complete Upper Receiver Group to swap between my Stag M5 6.8 SPC, & am in the process of looking into barrel lengths & or other related features. Honestly, it's not like I truly need it, as I have my LMT MWSE in 7.62 / .308 for whatever longer range shooting I may plan on, but I've been somewhat impressed with the cartridge's capabilities. ( At least in relation to anything I currently possess. ) I have noted a few Uppers by some manufacturers I've never even heard of. As far as 'name brand' units, I've only checked RRA & Stag Arms. RRA I couldn't fond anything in 6mm ARC, & Stag appears to only have complete Weapons available. Any input, or comments will be much appreciated, THANKS

Best, Dom P.