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 doesn't cut the mustard in this regard.
So paying from just £7.99+VAT for the privilege should perhaps be viewed as a bargain!
Our prices for our Ordnance Survey planning maps are here.