I like the look and feel of the shirts, totally brand-able!

I think that you should offer a percentage of all sales to Hive account@dan and Hive account@ned for the use of their copyright or trademark? After all this is their brainchild. Why not send them a communication about your shirts and get corporate approval to distribute products. Note: If you do make a deal to sell shirts can I be a re-seller? :)
Secondary idea: Customize each shirt with the members users name on the shirt, this would be awesome!

P.S. After thought: Are you missing an opportunity for sales, marketing and branding?

1. add the URL on the shirt.
2. Maybe incorporate a killer (one liner) message that tells everyone what the site is all about? (It could be fun, could be informational, could be the decentralized monetary message and much more).

These are just a few of my observations that you may want to incorporate for a SUPER POWERFUL T-SHIRT that nails the brand!

I hope this helps!