Bookstores in Mexico

Hi all. I am planning a trip to Mexico in the fall (leisure trip to Cabo San Lucas, B.C. Sur) and was wondering if anybody knows of a bookstore chain - or national bookseller - in Mexico that I can reasearch and perhaps order some geneaology books from.

Also, any ideas on upstanding book publishers (south of the border) that specialize in geneology finds???

All tips welcome.

-C