They're fairly rare, at least I've never seen one first hand. Dicks Sporting Goods sold them last year for about $800 but I never saw one at ours. I wasn't that interested because for the same price you could put together a better PSA or Spikes AR. I'd try to find the specs because it seems there were corners cut, surprising since it was Troy.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek