This is only tangentially related, but: It's probably really important to notice when you feel a desire to signal affiliation with someone or something by purchasing paraphernalia or, e.g., getting a bumper sticker. Wanting to signal that you like something generally means that your identity has expanded to include that thing. This, of course, can be both a symptom and a cause of bias (although it isn't necessarily so). See also all this stuff. Or, more concisely: "I want to buy a bumper sticker/t-shirt/pinup calendar/whatever" should sound an alarm and prompt some introspection. (I'm not trying to imply that you have a bias towards Paul Graham, just making a general statement.)

Looking briefly at a few sites specializing in custom bumper stickers, I estimate you could probably make and pay for some in half an hour to an hour. Do you want to do those other things that badly?