On Interesting Treasure: The Rare Star
It is very comfortable and the make is very high quality. To a decent tailor it will sell for 20 gold.
However this shirt design is also a model derived from an interplanar ideal. Certain rare formulations of this shirt allow travel through the astral, ethereal or in rare cases shadow planes. The duration is set by the fastening and unfastening of the buckles and travel is managed by the metal studs. It can function a limited number of times before it must be recharged in the light of a full moon.
It is said this design is copied from ancient memories of inter-planar travelers.
Gold piece value: 20 gp
Magical version: 18,000 gp.