We've been sending ours to Auburn University.  We mainly are concerned with pH for lime recommendation but their nutrient analysis is usually in line with our expectations.  Waypoint and others that are going to be who retailers send samples to are always much higher in their recommendations than Auburn.  We've had more than one farmer tell us they see the same thing.  Waypoint tested a sample that was inexplicably low in pH and P.  We planned to lime that fall as the crop was already growing.  Rechecked that fall and sent to Auburn and everything was normal.