Is there a good alternative to Photoshop available that won't cost me astronomical amounts of money?

Yup, there is indeed. It's called 'Gimp'.

It's open source, which means it's completely free of charge. It's also arguably the best free alternative to Photoshop and packs quite a bit of punch, although it's not exactly just as good as Photoshop.

Still, with it you'll be able to manipulate, enhance, retouch, paint and animate to your heart's content.

Give it a try — after all, if you don't like it, it wouldn't have cost you a thing other than downloading it!

Download Gimp at www.gimp.org