"This is the first ever Heath Ledger product to be approved by the trustees of Heath's Estate and have the endorsement of his family" the site simply explains.
The photo of Heath was taken by Ben Watts, a New York photographer and sells worldwide. If purchasing in Australian dollars, a t-shirt is $105 AU. Prices in other currencies are available and the postal fees are minimal.
If you miss Heath and/or admire his work, then this might be an ideal opportunity to buy a great t-shirt and support an even greater cause.