Stritcly speaking if you buy it and it comes with sources under the GPL then that is perfectly okay. The principle of freedom software isn't that everything is free of charge, but rather that when you obtain software you should be free to access its source and customize it for your needs and share those modifications with other people.
That does make it hard for people to really have to pay for it, but it's not like people don't pirate proprietary software anyway. The presumption is if you're honest and a good person you will pay the other for the software that you like and want to keep using.
It's also not violating the GPL by having proprietary apps alongside GPL ones bundled together. SteamOS for example, comes with Steam and other proprietary Valve stuff.
But I would definitely expect it to not be popular and for most of the open-source and Linux communities to want nothing of it (paying for a programming language, what is this, 1995 when we pay for Delphi?).