Hi,
Here is a list of some of the markets, got it from the tourist information but it was some time ago so not sure if 100% accurate.
Monday San Pedro del Pinatar.
Tuesday Los Alcazares, Los Belones and La Union.
Wednesday Cartagena, Santiago de la Ribera and El Mirador.
Thursday San Javier, Torre de la Horadada (afternoon only) and Los Urrutias.
Friday Torrevieja and El Algar
Saturday Torre Pacheco, Los Narejos and La Regia
Sunday Mazzaron, Cabo de Palos, Los Nietos, San Javier.Flea market on the service road between Los Alcazares exit Norte (mosaic arch) and the airport exit.