You can find MLB DNB stickers @
http://www.redbubble.com/people/djctoafn/works/16049166-mlb-dnb-black-on-light?p=sticker
I believe if you order more than 10-20 of the smaller ones you get them at half price so about $1 each.
They look banging on your car, laptop, random nightclub walls or street poles ;-P