Is there a way to get photoshop cheaper?

I want photoshop but I do not have $600 in my pocket. Is there any way (without pirating) to get it cheaper. Could I buy it used?Is there any kind of discount on certain sites? I do not need to buy it asap or anything I just would like to know for a future reference. I'm still very new to photo editing and stuff so I still need to research it before I buy anything. I have paint.net but it's extremely underpowred and I'm downloading gimp right now. Thanks a ton. :D