The #Debian tartan is currently not sold anywhere and must be made to custom order. If you'd like a piece of the tartan, or even a full #kilt, there is now the possibility to register your interest by entering your name and contact info into this pad: https://pad.stratum0.org/p/debian_tartan
It gets a lot cheaper when more people join!

For more info about the tartan design in general, see https://wiki.debian.org/Tartan and https://www.tartanregister.gov.uk/tartanDetails?ref=5936