I have both Paint Shop Pro 8 and Photoshop 7. If you're speaking in terms of just the software itself, I don't think you'll find a program quite as powerful as PS, thus the price.
However, PS has a really high learning curve...compared to PSP, anyway (I haven't tried the other programs mentioned). When it comes right down to it, though...any of the other programs can do just as well as PS, in the hands of someone who can use it well. Just looking at some of the layouts in the gallery is testimony to that.
You can invest in any of the less-expensive programs mentioned, and turn out a finished product that is just as good as one made in Photoshop, once you know the program and what it can do
