Whenever the county legislative authority desires to dispose of any county property except:
(1) When selling to a governmental agency;
(2) When personal property to be disposed of is to be traded in upon the purchase of a like article;
(3) When the value of the property to be sold is less than two thousand five hundred dollars;
(4) When the county legislative authority by a resolution setting forth the facts has declared an emergency to exist;
it shall publish notice of its intention so to do once each week during two successive weeks in a legal newspaper of general circulation in the county.