Since we forgot to mention it in the first place: Yes, we do have a 28c3-friends request address for people who can’t afford to pay the full ticket price. We’ve added information to http://events.ccc.de/congress/2011/wiki/Tickets:
If you or someone you know can’t afford to pay the full price for a ticket, send a mail to email@example.com. Please tell us, why this person can’t pay the full price and why he or she should take part in 28C3 nevertheless. Usually we agree on some affordable price. But please keep in mind that tickets are already very cheap and that we can handle only a limited number of such requests. So, please think twice before sending us a mail to that address.
If you want to try your luck, you still need to get a ticket in the on-line ticket sales. Just choose any ticket type and tell us the user name. If we agree on some price, we’ll edit your order afterwards. If we don’t agree, you may just not pay within 2 weeks.