Yeah, it is expensive to buy but erm.. I got mine through.. "other means"
If you can't get hold of Adobe Photoshop though, there are a couple of free photo editing suites that a lot of people use and get similar results with:
https://www.getpaint.net/
https://www.gimp.org
I haven't used either so can't say from personal experience, but I've seen some of what people have made with them, and they are really good. Apparently they have just the same features as photoshop.. just without the hefty price tag.
Hope that helps!
x