These couple weeks we have been testing compatibility with various brand RTK base stations. Alpha can work with Leica, Novatel, Qianxun, REACH, SkyTraq, Trimble, ublox, Unicorecomm RTK base stations. For latest update on RTK base compatibility, please check out this FAQ.
Currently most RTK correction source is paid service. The lowest cost approach is still using Alpha in base/rover pair, connecting to paid RTK correction service only to survey the fixed base antenna position for once when the rover latitude, longitude, altitude coordinates require centimeter-level accuracy. For relative positioning applications such as precision farming or grass cutting on a large field, then use of correction service is not needed when setting up the local base.