I currently use GIMP to clean up some of my Poser 7 renders.  It has layers and other good features. However, I see so many references and plug-ins for PS that I think I am going to have to bite the bullet. 

To get the most out of Poser, which version of PS do I need?

CS3 is $650.  That is some serious moola and not to mention the time needed to learn how to use it.

Are there lower end PS products (Elements for $100) that meet 95% of needs?

Thanks