http://gigaom.com/2013/04/06/how-to-build-your-own-adobe-creative-suite-with-cheaper-mac-app-alternatives/#_=_
Here's an excerpt:
Through apps mostly available via the Mac App Store, you can decide which components of the software set matter most to you and build up your own custom suite over time to meet your creative needs. Here are the best alternatives I’ve found that offer similar functionality to what is available in each of Adobe’s products.
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