We've considered this in the past, but it's just not really feasible for Keydar to do (or any of the "cast" really).
The two options are to setup some sort of thing with a company that does this sort of thing already. My current guild has done this in the past, and it's actually kind of feasible. The problem is, that this is T-Shirts only (maybe coffee cups too). You also need a certain amount of "buy in" to even make that worth it. Selling this to 5 people just isn't going to cut it.
As far as plushies or whatever, those are considerably more expensive for us to get created and manufactured. Which in turn requires a certain minimum amount of sale, that I just don't think there is enough demand out there for. On top of needing to store and ship this stuff. If we do it ourselves, well, ugh. If we get someone else to do it, that's even more cost on top of things.
So, maybe if someday Keydar gets very enterprising he'll setup something with a T-Shirt company, but chances are there won't be any DLC swag for you guys to buy :/.