It depends on if your municipality requires a soil report to ok concrete pour. But for the long term stability of your house, you need a geotechnical investigation, say no more than 2 borings to eliminate any low bearing or settlement prone soils not being in situ. If however, the inspector does not require a soils report, and you are comfortable with geotechnics, then you can purchase a static cone that tests both granular and cohesive soils, and it will give you the available bearing capacity of the soil. That cone runs around $850 and you can buy it from a company called "testmark industries" in the east coast. If you know you have cohesive soils, then purchase a hand penetrometer also from the above company or others and it runs around $60. Finally you could pay a soil testing firm under $300 and get a soils report and they are insured and will assume liability.