Sorry, new to blogging

I was wondering about the foundation.  I spoke with a representative who told me that the foundation is included in the cost of the house.  I then read the blogs and noticed something about the foundation only being skirting, not a basement.  Is this correct?

If so, would your company be able to make the foundation a basement?  Do you have an estimate of what that would cost for the larger model?  I just need an idea.