asking permission to print PHP logo for T-shirts

Dear Webmaster, We at Indonesian PHP User Group: http://groups.yahoo.com/group/phpug http://groups.yahoo.com/group/php-mania are planning to print some 50-100 T-shirts (well, initially, since PHP is quite popular in here. phpug has +- 500 members and php-mania over 200. We might print more if the demand calls for it). The design of the T-shirts will probably be like sketched in this page (although we are still waiting for more designs submitted by the community): http://kaosgeek.sslguarded.com/viewtopic.php?topic=9&forum=3&4 We are wondering whether we are permitted to print the PHP logo on those T-shirts. If not, we will probably invent a new logo. Also to be noted, this is not exactly a commercial endeavour, since I want to sell the T-shirts as cheap as possible. Regards, Steve