What is the most effective and cost efficient way to get rid of bed bugs?

I moved to a new city for a job. I found a place renting out a room from an older disabled lady. Everything is clean, but I'm being tormented by bed bugs. I used to wake up in the mornings in bed and see them crawling around on my sheets. (At the time I didn't know they were bed bugs, thought it was because my window was open at night sometimes.) I cannot sleep in my bed anymore as it's some kind of nest. So for the past three months I've been sleeping on the floor and they attack me every single night. My room is spotless clean and I just can't take this. I hear you can take bed bugs with you, so I don't want to move out until I can make sure that doesn't happen. The lady is too old to do anything to help me.