Section 134. Purchases by county purchasing agent

Notwithstanding any other
  provisions  of this article any county may, by a resolution of its board
  of supervisors regularly adopted, provide that all, or any part or class
  of supplies,  materials,  tools,  implements  and  equipment,  including
  purchase   or  rental  of  road  machinery,  required  for  any  purpose
  authorized in this article, shall be purchased or contracted for by  the
  county purchasing agent in the manner provided by law.