In my opinion accuracy is probably 60% barrel, 30% ammo and 10% other. So you could probably build a bottom end cost LR308 for all other parts, and put a noveske or criterion barrel on it and hit .5moa from bench rest or prone. Figure a low end upper/lower is $500, $200 for bottom end BCG, LPK+ cheap stock and lower completion $200, plain handguard and little junk another $100 and $600 on barrel could be pretty hot at $1600 or so. might not be the prettiest, might be finicky on magazines, etc but still should be ok. reliability might be a little different question, and for that you'd probably want a nicer upper/lower and more premium bolt carrier