Found the following on the "Sailing Pelagia" blog:
Sailing Pelagia: Information for cruising Mexico (charts, guidebooks, weather sources & communications) – Pelagia’s experience (2014)
I slightly reformatted and reprint below the bit on charts:
OFFICIAL
MEXICO CHARTS ARE AVAILABLE:
The Secretaría de Marina Armada de México (SEMAR) produces its own series of charts, and these are available directly from SEMAR in both paper and electronic (raster) form for the same price. The
SEMAR website has a full listing of these charts, indicating their coverage, scale, and date produced/revised.
I have seen some of these official Mexican charts and, at least the charts I viewed, they are considerably more accurate/up-to-date than the various electronic charting cards.
Unfortunately, these charts are priced individually, not as a package. At 369 Mexican pesos each (plus tax) – about C$31 for either format – a full set for
Mexico would be rather pricey. Another problem is that these charts are a little complicated to obtain: one has to contact a
government chart seller (for example, in Ensenada: Estacion de Investigacion Oceanografica de Ensenada, B.C., Boulevard Costero y Agustín Sangines (A y B), Ensenada, B.C. 22800 Tel. +52(646) 172 57 43
EMAIL:
oceanografia_eda@hotmail.com digadhicar@semar.gob.mx).
ALSO: Blue Latitude Press, publishers of the BEST
cruising guides for the
west coast of Mexico, has detailed electronic charts.
The detailed charts in the Blue Latitude Press guides are available as GPS-accurate charts for PC, Android, IPad and Mac. The charts are the same price for all platforms; however, software required to view these charts is expensive for PC and Mac, but quite reasonably priced for Android ("PathAway") and IPad ("INavX") tablets. See Blue Latitude Press and Fugawi X-Traverse websites.