Clutch problem.

What is your question?

While I was driving to work this morning my clutch went to the floor and I could not shift gears. My boss came and picked me up and after work I called the shop to see what they recommended, they said to check the clutch fluid and sure enough there wasn't any in. I added some and could shift while the truck was off, but did not want to shift while it was running. My boss started it in second and got it to the shop. They aren't able to look at it until next week but was wondering if it is the slave cylinder, how much it would cost at a shop, along with the price if it is just the line. Thanks much.