@Schol-R-LEA said:
For that matter, as Red Hat and the other major Linux distros demonstrate, open source does not necessarily mean 'distributed for free'. Under most open source licenses, including the GPL, you can charge for the service of distributing an open source program; you simply can't charge for the program itself (either the binaries or the source). More specifically, you can't forbid others from copying and distributing it for free. Plenty of people will pay for a well-designed distro, even now when bandwidth is dirt cheap.
Actually you can charge any price you want for selling GPL software, BUT you must include a written offer to provide the source code for free if you customer wants it. Ofcourse your client can do the same, though I've noticed that they rarely do. Probably because they've paid good money for the product (or customization of some GPL software) and they don't want their competitors to have it. And because they cannot offer any support for the software no company would buy it from them.