Cost to convert barn to house?

[Hen Ley]

I'm looking at a property that has both a barn and carport-  I would like to convert one or both to a living space and don't have concerns about preserving qualities of the barns interior structure for aesthetic reasons.  As a novice, I look at it an imagine it would be less expensive than a new build because the structure is already there, you just have to add plumbing, insulation, etc.  Is this correct, or is it a nightmare to try to convert a barn to a small house?  Is it less expensive than a new build?