A Snape fan isn't a Snape fan without a Snape shirt.
There's just... so... many...
I think the one I would most want is this one:
Which you can buy here: http://www.wbshop.com/on/demandware.store/Sites-WB-Site/default/Product-Show?pid=HPTVT14W&affiliate=froogle&src=FRGL
I mean, to have his face on your chest...
And of course, there's lots of others. But you need to get one. Or more.