I was actually looking for some geek themed printed fabric when I got to looking at Spoonflower - you can “design, print and sell your own fabric” which is awesome, not necessarily cheap though, but for something unique and designed by you not too badly priced.
I have no idea what I would want to print personally, but it would get expensive if you intended on using it for say a range of bags that get sold at a reasonable price, but for a one off thing / small projects I love it!
I found lots of robots. Oh Robot ♥
Then there is Horde Themed Material.
unfortunately there is no Alliance themed one.
So what do you think of a Horde themed sheet set – think your gf/wife/hubby/bf would mind sleeping in sheets printed with your gaming obsession.