A large variety of Demetri Martin merchandise is available on the web and here a few links to help you start your collection:

'These are Jokes' CD/DVD - buy it from Amazon.com

'Demetri Martin. Person' DVD - buy it from Amazon.com

'The Best of Comedy Central Presents' DVD (2008) - buy it from Amazon.com

'Invite Them Up' MP3 - buy it from Amazon.com

Demetri Martin Buttons - buy them from ebay.com

'New York Magazine' featuring Demetri Martin - buy it here from ebay.com

A large range of Demetri Martin joke T-shirts - buy them from zazzle.com

Demetri Martin 'Important Things' T-shirt - buy it from comedycentral.com

Invest in some Mensa puzzle book (what Demetri used to feed his puzzle addiction) - buy them from Amazon.com