I also agree on this one.
One thing I also would like to buy is promotional sets, that would include at minimum a CD/DVD with Linux Mint, and a leaflet with some images, information of what Mint is, how to use the Live-CD/DVD, some nice images, which included software that can be an alternative for their (for example) IM-client, etc. Some other small stuff like keyring holder and stickers would probably also fit nicely into such sets. This would be great to hand out to friends, people at different computer expos, LAN parties, and so on.
Speaking about apparel, I would rather go with a t-shirt with that other mint leaf logo that someone in the community made a while ago and have "Linux Mint" printed somewhere else with smaller text, it looks (my personal opinion) more trendy.