Along with other certainties in life like death and taxes etc, planning maps do cost money no matter who you approach. This is due to the detail of the mapping required for a planning application - it needs to show property boundaries and be up to date. Free mapping like that shown on Google maps and the like unfortunately don't cut the mustard in this regard.
To give the Ordnance Survey their due, keeping a nationwide map as detailed as they provide and that we use in our planning maps, is a massive, labour intensive undertaking..and therefore costly.
So paying from just £9 for the privilege should perhaps be viewed as a bargain!
Our prices for our Ordnance Survey planning maps is here.