Keep an eye out at Alcazaba Zoco — you're sure to come across some treasure or trinket among the stalls here. After you've admired the wares, try some fare from one of the food vendors.
If you love the word "free" as much as most people do, you'll be pleased to know this community marketplace is precisely that. Alcazaba Zoco is located in San Javier. To keep your sightseeing schedule full while you're in these parts, also stop by Mar Menor, La Manga Club and Calblanque Beach.