Here is the email I just sent to them.
This comes directly from the GPL itself at http://www.gnu.org/licenses/gpl-faq.html
"Does the GPL allow me to sell copies of the program for money?
Yes, the GPL allows everyone to do this. The right to sell copies is part of the
definition of free software. Except in one special situation, there is no limit on
what price you can charge. (The one exception is the required written offer to
provide source code that must accompany binary-only release.)"
AND at http://www.gnu.org/philosophy/selling.html
"Many people believe that the spirit of the GNU project is that you should not charge money for distributing copies of software, or that you should charge as little as possible -- just enough to cover the cost.
Actually we encourage people who redistribute free software to charge as much as they wish or can."
"Since free software is not a matter of price, a low price isn't more free, or closer to free. So if you are redistributing copies of free software, you might as well charge a substantial fee and make some money. Redistributing free software is a good and legitimate activity; if you do it, you might as well make a profit from it."
"The term ``selling software'' can be confusing too
Strictly speaking, ``selling'' means trading goods for money. Selling a copy of a free program is legitimate, and we encourage it.
However, when people think of ``selling software'', they usually imagine doing it the way most companies do it: making the software proprietary rather than free.
So unless you're going to draw distinctions carefully, the way this article does, we suggest it is better to avoid using the term ``selling software'' and choose some other wording instead. For example, you could say ``distributing free software for a fee''--that is unambiguous."
Now this is the real kicker:
"High or low fees, and the GNU GPL
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.
The one exception is in the case where binaries are distributed without the corresponding complete source code. Those who do this are required by the GNU GPL to provide source code on subsequent request. Without a limit on the fee for the source code, they would be able set a fee too large for anyone to pay--such as a billion dollars--and thus pretend to release source code while in truth concealing it. So in this case we have to limit the fee for source, to ensure the user's freedom. In ordinary situations, however, there is no such justification for limiting distribution fees, so we do not limit them.
Sometimes companies whose activities cross the line of what the GNU GPL permits plead for permission, saying that they ``won't charge money for the GNU software'' or such like. They don't get anywhere this way. Free software is about freedom, and enforcing the GPL is defending freedom. When we defend users' freedom, we are not distracted by side issues such as how much of a distribution fee is charged. Freedom is the issue, the whole issue, and the only issue."
So since you say that Mepis still falls under the GNU GPL and this documentation is directly from the GNU GPL website it seems that, as a company, you have no rights to dictate to anyone whether or not it can be sold and how much or little can be charged for it if it IS sold.
So yes, I will be contacting your legal department about this as well as the Mepis website.