Hi Poppet,
Not sure what days but there are some in Albufeira on certain days every month. Try searching the forum under "markets" and you should find some info'. We went to one in Quarteria quite a few years ago and it was interseting, mainly bedding, bags, shoes etc. Be prepared to haggle big time though
We drove to Loule also and went to the market there , we really liked it as the food, (veg, fruit, fish etc) were great and cheap. We were self catering in a villa so bought quite a lot of food there and it feels very much like a "real" market used by plenty of locals.
Good luck with the search
Lummie