Jeppesen is the main supplier to the aviation industry, and they have many different coverage packages at many different prices. For example, if your company only flew east of the Mississippi, there'd be no sense in having plates for LAX, etc. Most airlines have "tailored" coverage manuals specifically for the airports that are listed in an airline's particular Operations Specifications as being authorized for. The airlines pick-up the cost for each pilot. In the general aviation or bizjet world, it varies. I thing the rough price for a nationwide coverage is about $700 a year, which includes weekly revisions. Check out Jeppesen's site at (naturally) www.jeppesen.com for more specifics.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.