The Ordnance Survey charges a lot for most data, so what are the other options?
(The GeoInformation Group )
Has created Large Scale Data (1:1000)
UKMap's is more flexible licensing to Ordnance Survey
UKMap offers users the rights to retain any derived data they may create through using UKMap so increasing corporate assets and reducing investment costs.
Share derived data and UKMap data with partners, sub contractors and consultants through simple licensing options.
UKMap includes data layers that you would normally pay extra for: Addresses, Points of interest, BLPUs, Aerial photography,Terrain, Land Use, 3D buildings
*Note: Not all of the UK is currently covered , Most major cities are.
You could try MapMechanics - I have used them in the past for slightly cheaper data, and I seem to remember the used other providers such as NAVTEQ, rather than simply reselling OS data. They do provide simple prices for regions etc., which enable you to calculate the cost more easily.
There's a number of different digital mapping products available from Landmark