If you don't want to buy or can't afford the full version, nobody will supply an illegal link.
But you may want to look into GIMP, which a lot of people on these forums swear by and is free.
Choice of layer-based programs is sort of limited. I understand GIMP is similar to Photoshop so if you can use one you shouldn't have much trouble with the other.
Paint Shop Pro? After that I'm not sure.