Tianguis in Mexico are like "creativity" trade fairs, where cheaper, pirate, chinese and mexican versions of any product or object in this world can be found. If they don't have it, they will build it (copy it) for you for the next week at a lower price than the original. And not everything is counterfeit! There are also genuine mexican solutions to products that are complicated and expensive. Many toys and objects made out of wood and bottle caps (corcholatas), etc. Everything can be repaired with just a rubberband and chewing gum... and many other mexican inventions and solutions like those.
As a designer, I am not always happy with those solutions. In fact, I didn't accept some of my student's sketches with "mexican style creativity" solutions. I believe that at university level, ingenuity is fine, but that's not all. A designer has more potential as a creative mind than a "tianguero"... so, educated designers may develop clever solutions, not rubber band and chewing gum products!
When I was in Monterrey, my students did some projects for disabled people. We went to some private and public institutions to develop products according to their needs. Most of those institutions (including DIF) already had some mexican ingenuity products, not commercial versions, but hand made solutions with a rubber bands and a piece of cable. The goal for my students was to develop solutions for a reasonable price, but with the quality of a commercial product. The objective of that was to give some dignity to the users. You can see some of those projets at my web site.
Yesterday, I was looking for ergonomic information for disabled children, when I found PROJIMO and a book about their projects called "Nothing About Us Without Us". I must say that I was really impressed by the projects. I was fascinated by the stories about the people, and how they help each other, building a chain of support in the community. Suddenly, it's not "dissabled people"... it's Conchita, Mari, Raul, Marcelo, Rosa, Paco, etc, etc... those are real users, those are real people! They are not clients, customers or stakeholders... they are real people! We as designers often forget that, and just put them toghether on a melting pot and call them "market niche".