What source code you talk about? If I'm not wrong, all the source codes are in there, of course after installation, or if you concern about the first page that is index.php just right in the wamp folder. Hope this help
Actually, distributing GPL software (in this case, MySQL, phpmyadmin) means that you /must/ distribute the source code from the same place that you are distributing your binaries.
I've found the software really useful and would like to use it to distribute our IHRIS software (http://launchpad.net/ihris-suite). However, it is made difficult by not having all the original bits. For example, you have a couple of batch files that you've written to use during the installation process, but the installation process removes them.
Having the .iss file does make building the setup package easier, but it isn't enough to build the package myself. Nor is it enough to satisfy the license of the software you are distributing.