None. The data on the basemap belongs to Ordnance Survey and they charge handsomely for it, which is why Memory Map charts cost as much as they do.
The attitude in the US is different, not only the FAA Sectionals but also all of the NOAA Marine Charts are available free so I can download the charts into Foreflight on my iPad when flying and the marine charts into SeaIQ when sailing.
In the US the free provision of mapping data producs a distribution system that is cheap and efficient and facilitates commerce while the UK's way of doing things involves protectionism and charges that restrict the ready availability of the data. If we had the will to pay for it through taxation rather than through sales the unit cost would drop to next to nothing.
Last edited by Mike Cross; 2nd Oct 2013 at 05:18.