My most prized possessions clothing-wise are my three Rotorua marathon finishers' t-shirts for they are the running equivalent of the All Black jersey.
You cannot simply buy the t-shirt as part of your race entry fee, as you can with most other commerative race t-shirts. You have to earn it.
And to do so, you have to run 42.2km, clock-wise around Lake Rotorua, starting and finishing at the Gov't gardens in downtown Rotorua. It is only when you cross the finish line in a mentally euphoric but physically shattered state and then walk, with aching, screaming leg muscles, into the finishers' tent and show your race number that you are given a t-shirt.
If you don't finish the race, you don't get a t-shirt, even though you paid the entry fee. Too bad, otherwise.
They're not particularly flash t-shirts: just a graphic (different each year) of Rotorua, or runners, or the lake or some such on the front and the main sponsors' logos on the back.
But among runners they carry immense stature, for you've truly earnt it.