Retablos are simply a synonym for Ex-Voto, but as I've derived so much enjoyment from the first set I linked to I thought I'd link to some more on eBay.
(Keywords on eBay are very important, so having a variety of synonyms for the item you're looking for can be useful in acquiring a bargain...)
eBay search Retablo (click here).
One my son would appreciate, a woman giving thanks to a Saint for ridding her house of giant spiders....

Here a woman gives thanks to the Saint for ridding her home of Corn Demons. OK.

And here we have children playing with ghosts. Judging from the look on her face that's not a good thing, although the children don't seem to mind....

The Saint is apparently removing gambling demons from the petitioners bed....
Here I'll refer to the translation on eBay: "María Luisa Rodríguez bored him a lot his pretenders because all were flat and predictable and also ugly. Until she knew Pedro López that won their heart giving him a carnivorous plant. She thanks to San Antonio because him is an original and intelligent man and until he has beautiful eyes. Also with the carnivorous Plant no longer has flies neither mosquitos in their house. "
Hmmm. Not only romantic, but practical AND Carnivorous... and to think I used to buy girls jewelry!!
This one as well has a very curious interpretation: "A gigantic and very strange bird, full with sharp teeth, came every night to eat up to my chickens and my rabbits, I defended them with my broom but when I fall asleep it always ended for stolen some one. I elevated my prayers to the Virgen de Guadalupe and thanks to her intervention the huge prehistoric bird returned to the mountains that it is of where it had come and it left in peace the animals of my farm." Someone should advise Loren Coleman, there's an expedition just begging for funding....