Municipalities are hereby authorized to purchase products and/or services manufactured or provided by sheltered workshops and programs of the department of social and health services. Such purchases shall be at the fair market price of such products and services as determined by a municipality. To determine the fair market price a municipality shall use the last comparable bid on the products and/or services or in the alternative the last price paid for the products and/or services. The increased cost of labor, materials, and other documented costs since the last comparable bid or the last price paid are additional cost factors which shall be considered in determining fair market price. Upon the establishment of the fair market price as provided for in this section a municipality is hereby empowered to negotiate directly with sheltered workshops or officials in charge of the programs of the department of social and health services for the purchase of the products or services.