I think most companies want this but have no idea what it means - designers need to work in pairs - who is going to check their work if they are on their own? This needs to be run as a separate division with resource for design library, software, hardware, PI Insurance etc etc (which only pays out on checked work!). If you only want one designer you better make sure he is the dogs bollox - current market rates for a designer who can stand on his own two feet without being spoon fed are c£80-90k salary plus employee on-costs. Maybe those subcontract designers aren't so bad after all?
You might get lucky and get a mid-experienced designer for less but are you going to keep him when the design offices are paying this??