If you guys haven't heard of RiptApparel.com yet, here's my recommendation.
Each day RiptApparel.com provides 3 designs available as t-shirts, hoodies, posters, and . . . coasters(?) for some reason???
The designs are always a part of geek culture, be that anime, comics, movies, etc, and they're affordable also (as of Jan 2015, $11 for a t-shirt + an expected amount of shipping & handling). For instance, this weekend they had a couple Deadpool shirts, a Big Hero 6/Iron Man mashup, Attack on Titan, My Neighbor Totoro and a Neon Genesis Evangelion.
What really gets you is the fact that the designs are only available for 24 hours at the normal price, and an additional 12 hours at an elevated price (+$5).
This means that #1, there's no "waiting for a sale", and #2, when you buy a design you can be relatively sure that you are going to be one of a very select few that owns that design.
Now, the artists that provide content for the site are (I believe) allowed to take their designs elsewhere, so it may be that you can get the shirt in some other manner down the line, but it's still a very effective marketing technique for Ript.
Also, some days are better than others, but there's rarely an entire week that goes by where I don't want (or actually buy) one of their shirts since I came across it.
I'm not getting a kickback for recommending this site, I just think it's awesome (and a little troubling since they've got me hooked — my fiancee and I have already bought something in the order of 10+ shirts/posters from Ript, but considering that we would have spent 2-3 times as much buying them at Hot Topic and they're higher quality and more unique at Ript, well I guess it's a good thing!).