Well, when I call around next week if everyone is $6-$8 then I'll be at $5.99... no reason now to be way under market... but if market is $4 then I have no issue with it. BTW, banners represent about 1% of my yearly sales.
I tend to price larger jobs right in the middle most of the time. Based on feedback I get, sometimes I'm way high, sometimes way low.. but I like to be right in the middle. I think it's harder for people to shop larger order that require site visits (vs calling around for banner pricing) so I tend to price those higher and rely on my portfolio, reviews, turn-around time and charm to win those.
I stopped doing small order yard signs and magnetics because I had a high price on them. I hated the way people would sound disgusted when I told them my price on them and felt better just telling them we don't do those orders.
You might want to call around for the types of work you do the most of also to test whether or not you're in line with most other equally qualified and equipped shops.