According to this fee schedule from the University of Florida soils lab:
http://soilslab.ifas.ufl.edu/E...
it costs $3 for a pH test and recommendations, $7 for testing pH, lime requirement and the major nutrients phosphorous, potassium, magnesium and calcium. Presumably you can drop the sample off at your county extension office - I don't know the price of the home test kit you're thinking of but I imagine it would cost more than that?