Even if you are paying cash for the floating home, I highly recommend every prospective buyer obtain a float inspection.
A float inspection costs around $750 and the buyer customarily pays for it.
Skipping the float inspection in order to save $750 is not recommended.  Not knowing the condition of the float prior to purchase can cost a buyer up to $100,000.
The house inspection is separate from the float inspection.
A home inspection costs around $350 and the buyer customarily pays for this as well.
In total, buying process inspections for a floating home will cost a prospective buyer around $1,100, regardless of whether or not the deal closes.