It's not difficult to do at all my friend. A receiver set, a high quality barrel, a real nice trigger, aftermarket safety levers and mag releases + LPK, buffer tube, springs and buffer, bolt and BCG, free float handguard, gas system, BUIS and Optics, and muzzle device. Go price the least expensive of all these items that are a component of any typical build and come back with your total. You will find that even the least expensive components add up so very quickly, this is compounded by the prices you will pay for the higher quality components that you can confidently stake your life on.