Where can you buy real liver (pref. calf's liver) in the western US?
Have you asked the meat departments of the stores you shop in?  They may not carry it simply due to lack of demand but could order it for you.

Calve's liver is often sold frozen in small quart size containers due to the fact it's not a high demand item.  Check your freezer section as well as the fresh meat section.

Also look in the yellow pages of your phone book for any meat markets in your area.