[Crinus]

Note that source code access and FOSS are orthogonal. AFAIK in older Unix systems software you'd buy would often be in source code form. In fact at the past severa lLinux distributions had a lot of such software.

As an example Slackware distributes a shareware image viewer/manipulator called xv (which was very popular once upon a time): http://www.trilon.com/xv/

It is the license that makes something FOSS, not being able to compile/modify the source code.