Hm, normally I would fangirlsquee and would say: "Omfg yes, let's do this" but I know very well how much work it is to make shirts, banners, tea / coffee mugs, bags, buttons and whatever you can imagine and merchandise. It's a hell of work and you need a lot of time, skilled people (the merch. should look "awesome" too), a lot of time and then you need money to print things on shirts and so on.
It's not like it is REALLY expensive but you have to consider aarin have to make prices so they could "earn" something for their work. And I would support them to do so because they shouldn't do anything for free. I mean, it's a hell of work (I repeat myself...I know) D: !!!11
If you use images from manga/anime you have to be careful about copyright and more. =_o Or you have to draw something by yourself....(work)
To be honest this should be a project (if you like to create merch.) with team members without responsibility for the site, the forum, the translation and the fansubs because it's much work and you have to spend a lot of time on it. Maybe some people who want to help voluntary or so.
Urm, but I wanted to ask if you'd be mad when people make 'merchandise' (like shirts) with "I'm proud to be an aaringirl" without the link to the homepage on the bag of the short or something like that (only for 'private use').
(If you try to create your own merch. it would be better and more comfortable to leave the link to the site out.
That makes life easier (for you and me). And so only those who know what aarin is know what the text means?)
(guh, sorry for my English :/ )