I do my own.

I still have serious questions about the value of soil tests.

I have these questions BECAUSE of the number of results I have read....results that often defy explaination. 

One thing I will say for certain, after thousands of grid samples....going out to a field and pulling one sample and testing it is worth absolutely nothing.  I would sooner just guess and assume it is 'average' because at least you would be less apt to screw something up that way.