The arrangement would be similar to London City and Luton - NATS Airports pays NATS En-route for the approach radar services and this is in turn, funded from the contract price with the airport.
Technically, if NATS Airports was willing to absorb the additional cost of ATCO 2s at a Band 5 unit providing the service, yes it's feasible.
But given NATS Airports' new commercialism, it's unlikely.
One 'wild card' is that the Single European Sky (SES) initiative actually sees all air traffic control provision being done through direct charges on the users i.e. aircraft operators.
Therefore, if this became standard practice under SES, it would be the actual cost per flight that dictated where the service was provided from and it's probable that the cost would somehow be 'lost' in the overall Eurocontrol route charges protocol and so be transparent to the aircraft operators.
All very
....