Brownells was recently selling 14.5" DD uppers without charging handle, bolt carrier group or FH/muzzle brake. Might see if they still have any in stock. At one point they were on sale and Brownells also had a coupon code, so very competitive price. I purchased one (my second) because I couldn't resist the price and I already had an extra charging handle and BCG lying around and have a Dead Air suppressor in jail, so I wanted to put key mod compatible muzzle brake on it. Just have this upper sitting around for now, but suspect I'm going to have Dead Air muzzle device pinned and welded to just avoid the whole SBR thing once my suppressor comes through.
One word of warning ... as someone whose admittedly pretty baffled by current (and proposed) ATF rules on pistol braces, I think you need to be careful. If you put a pistol brace on a 14.5" upper do you end up running afoul of over all length restrictions? I'm asking because I'm honestly not really sure.