Location ? Check with you local building department and see if it is a requirement for the permit. Probably a good idea anyway. Very soft (sandy/ deep organic) are difficult to dig in. The sides fall into a trench very easily.
If you are planning on the whole structure having a cement floor, I don't think a pole building will save you that much money.
Is part or all of the building going to be heated or cooled ? If so, you should look into using SIPs. They are not cheap, but install fast and you will have a well insulated building when you are done.
Last, if you are going to heat and/or cool the building, install insulation and vapor barrier under the floor !