Sounds like you're a few steps ahead of me in opening your shop, but I would suggest you open up your website sooner rather than later. We've picked a name, and as soon as we've designed our logo, we're going to at least put up a professional "coming soon" splash page.
Why not? Registering a domain name and getting a basic hosting plan is pretty cheap. You'll be able to get a nice (you)@(yourcoffeeshop).com email address to do business out of. You can put the email address and website on your business cards, confident that info won't change later.
I believe there are some hosting company recommendations in the archives. Personally I've done business with godaddy.com in the past and had a good experience.
I am using Mocha Host for my website. They are very responsive with technical questions and I haven't had any problems with them. I think it was $44 a year which includes domain name registration and I get to keep my domain name for life as long as I stay with them.
Well, we registered our name www.prattshillofbeans.com. And we just signed our lease. I like that I now have an email address that looks more professional than my personal address. Thanks for your help! The site isn't up yet, but I have someone working on it.