Soil Sampling Equipment Recommendation:

Option One:

JMC Environmentalist's Sub-Soil Probe ($2250-$5350)
Even though it requires plastic liners, this probe still deserves consideration. It features a sliding drop-hammer and a foot-operated jack. Great system for all soils now and more capabilities later.

Option Two:

JMC T-Handle, Mallet, and JMC Sampling Tube ($170-$665)
Inexpensive method for sampling hard soils.