I have a few HRC shirts: Amsterdam, London, Maui, Rome, and Sydney; but when it comes to collecting HRC merchandise, I stick to pilsners and pins, and collect them only as I physically visit each HRC. I have them from:
Amsterdam, Barcelona, Berlin, Cologne, Copenhagen, Denver, Hollywood, Honolulu, Key West, Kona, La Jolla, Las Vegas, London, Los Angeles, Maui, Madrid, Munich, Myrtle Beach, New York, Newport Beach, Orlando, Paris, Phoenix, Rome, Sacramento, San Diego, San Francisco, St. Louis, Stockholm, Sydney, and Washington DC.
...with more to come, I hope!
It's an entirely different kind of flying; all together.