Mr. Brown,
I don't think devloping Baldonnel into an international airport is the solution to the NIMBY problem, just look at the problems Weston has run into in the past few years.
Now just super impose Dublin airport's opeartion flying all over Baldonnel and I'd say you would have a few complaints!
True Dublin could do with a 'new' airport, but I don't see anything wrong with it's current location. So with a new airport will come a new runway and terminals, I don't see a runway as being a 'cheap' solution to the problem, and I don't think 3000x45M worth of concrete will be cheap!
MK