Cheap price on L4D for pc?

[TheRobReport]

So I a friends girlfriend said she would let me borrow her pc to play left 4 dead with her on it, now I just need the cheap copy of left4dead on the pc to play.

 

[i3uu]

check out steam if you haven't already

 

[TheRobReport]

I did before I posted, it was $19.99 retail.

Was hoping for something a little better than that