Except as provided in Section 9000.5, in a stepparent adoption, the prospective adoptive parent is liable for all reasonable costs incurred in connection with the stepparent adoption, including, but not limited to, costs incurred for the investigation required by Section 9001, up to a maximum of seven hundred dollars ($700). The court, probation officer, qualified court investigator, or county welfare department may defer, waive, or reduce the fee if its payment would cause economic hardship to the prospective adoptive parent detrimental to the welfare of the adopted child.