When the light bulb was cheaper and better, we ditched kerosene.
For such buried deposits boring is cheaper than sinking.
It was before 6:30 so the early bird special was in effect, making the meal a tad cheaper than he'd figured.
It was in general cheaper to buy a slave than to rear one to the age of labour.
Through the advent of German and American fur sewingmachines since about 1890 fur work has been done better and cheaper.