From a store called Stitches. They've got lots of animal hoodies, One Direction clothes (ugh), and even some other cute tops like the trend (I blame Romano for that, hence the icon). I've even seen someone with a t-shirt that said "Keep Calm and Eh On", and I think I also saw one that said "Keep Calm and Drink Tea", but I think that might have just been a poster.
Sorry that the reply's kinda long, I rant a bit sometimes. But I'm not sure if there's a Stitches in the US, but I do know there is a store called Hot Topic with other Hetalia shirts.
Stitches? I'll have to look into that. I hope they have American stores, but if not, I'll have to get things shipped... Hahaha I've never heard of that one! XD
That's all right. I write long responses at times, so it's really no problem. Ah! Hot Topic! I recently went there and found a bunch of Hetalia stuff. I bought almost all the Hetalia stuff there ($80 or so) and there were other fandoms' merchandise there too. ^^
BTW, they also have "Keep Calm and Be Awesome" t-shirts at stitches. I forgot about it until I found it buried in my closet this morning.
I'm so jealous! I heard that there were no Hot Topic stores in Canada, but when I saw some girl at my school wearing one of those shirts, I had no idea anymore. I think she was kinda freaked out when I kept staring at it while she was wearing it.