you looked into gimp? open source (and therefore free) program much like photoshop... due to it's open source roots, it's a bit more jagged on the edges, takes a little more doing for most things.. but in the end, the pricetag can't be beat... plenty of users here use it almost exclusively, and there are plenty of gimp-based tutorials.. i'm not sure if you can import ps documents, but i wouldn't be surprized.
take a look!
GIMP - The GNU Image Manipulation Program