I created some T-Shirts on www.goodstorm.com. The least expensive ones are $6.95 and it goes up from there. Certain sizes are a bit more, certain colors are a bit more. The markup is only $1 to make them as affordable as possible so more people can buy them. Any proceeds go to the campaign.
https://www.goodstorm.com/stores/carla8478
https://www.goodstorm.com/stores/carla8478