This is just my opinion, so take it for exactly what you paid for it, but there is no reason to pay that much for an AR. I mean, you can spend that much on a Daniel Defense or an LWRC but for the every-day shooter, you just won't see the value in the extra $1500 over a Ruger, S&W, Rock River, Armalite, or one of the higher end PSAs.
For the SBR, rather than buy a whole gun and go through the Form 4 process, I recommend buying a complete lower, submitting the Form 1, have it engraved, and then when the Form 1 is approved, buy the pistol upper and rock on.