If a contract for sale or construction of a new home between a buyer and a builder who participates in a new home warranty security plan provides, either by its terms or by virtue of an option exercised by the buyer, that the home will be registered in the plan, the operator of the plan shall register the home and shall do so at the cost agreed upon between the operator and the builder and disclosed to the buyer at the time the contract for sale or construction of the new home is entered into, unless the buyer is not charged directly or indirectly for the cost of the warranty. Protection under the new home warranty security plan begins on the warranty date. The provisions of Real Property Article, Subtitle 6, Annotated Code of Maryland, concerning new home warranties apply to each newly constructed private dwelling unit, the contract for sale or construction of which is entered into on or after January 1, 1991. The provisions of Real Property Article, Subtitle 6, Annotated Code of Maryland, do not apply in Montgomery County, except as provided in Real Property Article, §10-610, Annotated Code of Maryland.