Charging ($20) for GPL source?

[Peter Roozemaal]

MI wrote:

> Synology distributes it's firmware through downloads from it's website
> (see http://synology.com/enu/support/download.php)
> 
> But the GPL source cannot be downloaded. It can only be ordered on CD
> for a fee of $20. (see http://synology.com/enu/gpl/index.php).
> 
> Is that OK, by the GPL? As I understood it, if the binary is offered for
> download, the source should be as well.

Citing the GPL (http://www.gnu.org/copyleft/gpl.html)

3. You may copy and distribute the Program (or a work based on it, under
Section 2) in object code or executable form under the terms of Sections
1 and 2 above provided that you also do one of the following:
[...]
b) Accompany it with a written offer, valid for at least three years, to
give any third party, for a charge no more than your cost of physically
performing source distribution, a complete machine-readable copy of the
corresponding source code, to be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange;

I've seen a written offer; $20 doesn't sound horribly expensive for
burning and shipping a CD-ROM. Looks OK with me.

Peter.