If you jail broke the Mac OS/x then you could have anything and everything for free but for now you can download the free Linux Gimp photo editor for the Mac. It has all the same features Photoshop has, you can download it from here

http://gimp.org/

If you want to take a look at what Linux operating systems have to offer for free check these web links out by the way these won't run on the Mac, you would have to download the Linux distributions that's design to install on the Mac then download and install the free software you want ilke Gimp

Linux Video Editing systems

http://www.bandshed.net/AVLinux.html

http://ubuntustudio.org/

http://dreamstudio.dickmacinnis.com/

Linux distributions that WILL install on the Mac If you have any questions about the operating systems then use their users forums where you will get all your questions answered.

http://gentoo.org/

http://debian.org/

http://fedoraproject.org/

http://suse.com/

Now the rest is up to you, I've done my bit to educate you on how to save money and be a uncontrolled free person

Intensify Pro is definitely worth more than $50! I've been using the program and it's amazing. It's perfect for all skill levels. It allows you to create powerful images with great detail. It's easy to use and always helps you create beautiful images.

Lightroom 5

Pixelmator