cheapest Photoshop/art program

What is the cheapest Photoshop/art program that has the line tool? So in other words, NOT ELEMENTS. I have Photoshop Elements 8 already, and it does not have the line tool. If you have any other program suggestions please keep in mind that I’m an artist looking to create digital artwork. Also note that I DO NOT WANT any links to places where I can download Photoshop for free. I’d rather not risk getting sued.

Krita or Gimp. Both open source and free. I think Krita has best support for the photoshop format if you need compability with your existing files.