Some time forever ago (August), Captain Canuck, writer of Waxaholic and other blogs, sent a PWE my way via San Francisco. The envelope finally made it here last month, and I think I'm just about caught up with my trade posts from last year. He sent me six stickers from the 2012 Topps Stickers set toward my set!
this post makes me think that I still need some stickers from 2011.
I haven't tackled the 2013 set, but if I find a box cheap (doubtful, but you never know) I'll probably make a go of it.
Anyway, thank you, Brian, for the help!