You can get a completely assembled upper and all you have to do is put it on the lower but it depends if you want the to gain the experience and knowledge that goes along with assembleing it yourself. I built a RRA m4 from scratch with no problem but there is an extra expence for the necessary tools to do it right such as the reciever block for the vice, barrel wrench, the necessary punches, hammer and torque wrench(which most have already),etc. With that stripped lower you do have to get a lower parts kit and an A2 stock which should have the buffer tube, spring and buffer with it and your lower is done. Should only take you 1-2 hours to get that lower done. Never dealt with neither of those dealers but I can suggest Pete-in-NH or Georgia Precision. They both deal in RRA parts. Check them out on the Equipment Exchange. I know Pete can either build the upper for you or send you the parts and he is super fast on his service.