The Collaborative International Dictionary of English v.0.48:

Tag sale \Tag sale\, n. [From the price tag usually attached to
   each item.]
   A sale of usually used items (such as furniture, clothing,
   household items or bric-a-brac), conducted by one or a small
   group of individuals, at a location which is not a normal
   retail establishment.

   Note: Frequently it is held in the private home or in a yard
         attached to a private home belonging to the seller.
         Similar to a yard sale or garage sale. Compare
         flea market, where used items are sold by many
         individuals in a place rented for the purpose.
         [PJC]