Why are the electronic charts so expensive though?
My guess is that Memory Map has a certain pricing policy which they run on their main product (the O/S 1:25k etc maps for walkers, etc) and they have applied it to the CAA data.
And they probably didn't know anything about aviation so took a stab at what they thought the market would stand.
To say more, one would need to know CAA's pricing on the data they sell to MM. It is possible that much of the £50/CD price tag is the CAA fee, but I doubt it.
One thing is for sure: the sales of the MM CDs are far far lower than the sales of the CAA paper charts.
To have a chart when flying is a legal requirement
It isn't actually, and this is true in the UK and the USA. I think there are some 3rd world countries where you have to carry the printed chart. Here, you just need sufficient navigational data, in any form.
I agree entirely that downloadable electronic charts (which the pilot could print off for the required area) would be a big safety improvement, especially ones that could be run on electronic gizmos as a moving map.