Exactly, that's why I want to work out a deal with them.
Jourdy,
You might start with a simple e-mail to Craig / OpenPandora asking if they'd be open to the idea of you putting together a proposal. An actual business plan like proposal, rather than a forum thread. They're the ones with the... well, not purse strings, call it control strings.
From there you'd handle it professionally. Get a mock up at the least - and the details of how you're going to do the merch. CafePress and the like have a much higher per unit cost then the print 1'000s of Ts companies, but a much lower startup cost / minimum order. An important consideration since the group to purchase the Ts is less than 10k. (Don't know how many iControlPads purchasers there are.) Working directly with Craig / OpenPandora directly is really the only way I see to go forward. You'll want to consider what specifically you intend to merchandise first, what their cut is, what your cut is, what the cut of the T-shirt manufacturers is, how many of the things you're going to produce, WHO's going to produce them, etc. You'll want to do a bit of research before the initial e-mail so if he asks questions you can answer them.
A few went the forum route, but it went nowhere. This may go nowhere. As soon as the Openpandora team has a moment to breathe they may very well want to produce their own merch, they may not want merch at all, etc., etc.
Cheers. I wouldn't mind seeing some OpenPandora / iControlPad merch, but as somebody else said, it's tricky. What percentage of the ~4k people who ordered a Pandora would purchase a T-shirt. If it's 50% - maybe optimistic, especially since some may one one design and others a different - then that's only 2k shirts. What're the costs involved in doing this, how much profit can they see from the shirts? (And you can't bump the price of the Ts up TOO much, it makes the people willing to purchase group smaller.) If you can't get the profit up above 5k for THEM, I'd be surprised if the idea gains any traction as the bother of working out the details...