Alright, here's my suggestions within you budget.
First $400 is for tax stamps.
Next is the gun.
I'd buy this: http://palmettostatearmory.com/index.ph ... upper.html
and rebarrel with this: http://palmettostatearmory.com/index.ph ... arrel.html
(When it's back in stock and have it cut down to 8" prior to installation.)
Once you get you lower $250 for a PSA MOE, register it as an SBR and in the mean time you can wait for the 300 BO brl to come back in stock and have the work done. SBRs are taking 6 months!
Now, call me a fan boy but I suggest a Innovative Arms thread on Deception 7.62 can over a YHM. Here's why, the overall length is shorter on a thread on can and the are more baffles in the IA than the YHM. The whole point of a suppressor is to be shorter, quieter and suppress flash. Why have a QD if it's louder, flashier and longer?
That will run you $750. So far we have $400, 750 and the upper and lower which is $600 then the brl which is $250. So were roughly at $2000.
I'd skip the optic and get some Daniel Defense fixed sights with a tritium front post. That's $200.
$2000, that leaves you with $125 for a YHM carbine rail. $2125.
I'd spend the rest on 300 BO ammo and AR-15 mags.
Yeah, it may be a little more heavy but I've been using YHM, PSA and DD stuff for a long time and none of it has failed.
Personally, I'd skip the BO and get a 5.56 AR-15 SBR with a 10" brl and a IA Grunt suppressor. Get some sub sonic 5.56 and call it a day. That would be hundreds less and have common parts with every other AR-15 on the planet.
The problem I see with the BO is while it will cycle subsonic you still have the noise of the action. Go ahead, cycle the action on an AR, it's still loud. Now, with subsonic 5.56 I can fire a very quiet shot and cycle the action when I want to just by yanking the charging handle. You know what, I have a decibel meter on my phone, the cycling of an AR reads out at 87 decibels.