Agreed, I just recommended an add on heat pump. If he has a similar age a/c the coil may be a heat pump coil and he might be able to merely switch outdoor units (contractor) if its a match. His payback would justify the cost and he might get a rebate for it from the electric utility.
Thats what I would do. Or then again get on the budget plan with the gas co. and grin and bear it when the settlement bill comes.