most of this came with my setup so i cant quote price but the little bottles of drops are only a few dollars at pet departments in wal-mart
the rapidtest soil meter is cheap but not very accurate...leave it stuck in the soil a full 15 minutes for a pretty close reading
the tri-meter (blue thing with wires) tests the water i feed with for ph,ec and temp
the meter stuck in the cup of soil is about $50 and works great,a control wizard accurate 8