Speaking as a European, I'd rather just donate a fixed amount of money than buy anything to support our boards. Why, you ask? Because shipping is expensive. And I'd rather donate 20 bucks to the site than donate 10 $ (by buying some shirt) and pay 30 for doing so.
However... if shipping cost can be reduced to a minimum, I'd be willing to contribute in a way I feel comfortable with. Remember the S-shield friendship bracelet? Hint: it looked like this:
I could do some shorter versions as keychain pendants if we actually do this auction thing.