There's nothing wrong with selling GPL'd modules: the GPL does not state that you have to give software away for no cost, only that you must make the source code reasonably available.
According to the Faqs (Thanks to IlyaM for the link :)...
Except for one special situation, the GNU General Public License (20k characters) (GNU GPL) has no requirements about how much you can charge for distributing a copy of free software. You can charge nothing, a penny, a dollar, or a billion dollars. It's up to you, and the marketplace, so don't complain to us if nobody wants to pay a billion dollars for a copy.
I was under the impression that the GPL specified you could only charge a "reasonable rate" for distributing the software. I was obviously wrong about this and your first statement is correct.
The other nit, why are you worrying about having to supply a copy of the GPL? You can't inform a user of their rights without giving them the licence: this isn't GPL specific; the same applies with any other licence.
I don't think I fully understand what you're saying here. Surely you're not claiming that I shouldn't supply a copy of the license because if they do not know their rights, they can't use them?