I'll just throw this in there, while it's a hot topic. When they were still selling their Monolithic platform, I bought and built a SR-25/style .308 off of the Mega Arms MA TEN platform, based on using DPMS compatible parts. Here's the final rundown of the parts list:
Mega MA TEN Monolithic Rifle Length chassis (upper & lower)
Fulton Armory 18.5 Mid-weight Rifle length gas system
Fulton Armory Titan bolt assy.
FA low pro aluminum gas block
SI Defense Nickel Boron bolt carrier
PACT SR Gold trigger
Battle Arms BADASS (saftey lever)
CAA G17 Grip
Magpul PRS stock, Magpul rail covers, Magpul mags
Bobro/GG&G Bipod
Ops Inc. 12th Model muzzle brake and suppressor combo
LaRue Tactical QD 10MOA single piece scope mount
The only custom work that this rifle has ever seen, was the tapered collar for sealing the rear of the suppressor, which I machined myself and was only an additional component for assembly. All I did was put all that together, basic assembly required, and no fitting of any parts with the exception of the aforementioned collar. The beast easily shoots .75MOA with sub grade match ammo, and .5MOA with FGMM and comparable ammo. The total price tag for all that comes up to the $4k mark. Would I do it again? You bet! I know my rifle inside and out, and I can't reasonably ask it to perform any better.The OBR is a fantastic piece of gear, but had I built my same design off that platform, I would easily be at the $6k investment mark.
The short answer is that a Franken-rifle CAN meet or exceed it, but you have to buy premium components to do so, and while you might end up coming out cheaper still, the margin won't be exceedingly wide.