"Drones," or as the current acronym goes, RPAs, cannot only be counted in terms of unit cost. They don't work without the ground stations for control, DGS for exploitation of the sensors, and satellites for ever increasing bandwidth. Add all that up to get the true cost. Other stuff, like ammo and maintenance, ATC, fuel, are across the fleet costs regardless of manned or unmanned, and may go up or down, but not in major dollar terms.
Only thing you save in terms of avionics manned vs. unmanned is human engineering and survival mechanism costs. Most numbers I've seen for these systems is on the order of $1 million per system. Not inconsequential, but cheaper than the equipment, bandwidth and manning costs of the support network needed for RPAs. That, and you can still bomb Libya with RPAs while telling the American public and congress that you don't need to ask for permission 'cause you're just supporting others with ISR, tankers and SEAD, but "not sending manned bombers" into Libyan airspace.
Wasn't the argument in 2009 that we could cut the F-22 line because the F-35 would soon be online and provide enough capes to cover the gap?