Funny, I am going to pick up my shirts and jacket from the embroider tomorrow! I went in to talk with her about shirts, she had known I did web services, and so SHE actually brought up the topic of bartering. I would have if she didn't, but always good when they do first.
Anyhow, I tossed together a basic website package deal and sent it her way for the shirts and jacket. Very nice stuff too!
The way I see it tho, I am more in over all end ticket. However, cost up front she is more out of pocket. It costs me very little to get a year of webhosting and domain, however, she had to buy my shirts and jacket. However, I will spend more time working on her site than she will my jacket and shirts.
I think if you are willing to deal locally and with smaller companies, bartering will come up a lot. Just remember to not under value yourself. I did this because I was so excited to get my shirts and I'm so used to giving services away for free to friends and family. But I'm coming around...
Good luck, hope you get some nice shirts! Don't forget a jacket/hat/etc if you're in cold weather or you want some style points.