1999 Buick Century burning excessive oil

My car is burning a lot of oil. I had my scheduled oil change in December, and not due until I hit 117347. But I took the car back to Firestone last week, because my low oil light came on. They told me that I was like a quart and a half low on oil. They topped it off and sent me on my way. Later that same day the light came on again, but went out. Every day since that light comes on, but goes out. Also I've noticed that I've got this light ticking until the car warms up. Yesterday I took it back because it looked light the oil was gone again. They told me that the oil was low, and that I had a loose lifter. I have no smoking. What should something like that cost to repair?