You were thinking of building one yourself? So know HTML, or can use a program like Dreamweaver, FrontPage, etc.?
If so, then look into godaddy.com, or another hosting site. I'm not a computer programmer, just a bio degree, but i have a website for both my parents' practices. The things you will want in order to look professional is your own domain name! like
www.smithfamilydental.com. (that is not a real site, but it hyperlinks automatically...). So be sure whatever you do, that you get your own domain name. You can buy one from loads of companies like godaddy.com or any other hosting companies.
Remember, no smithfamilydental.tripod.com (or anything similar) <-- looks very unprofessional and cheap.
Edit: and the other thing is, make sure you use a hosting company. Its a few bucks a month, and if you try to host it yourself, even on a dedicated machine, it will inevitably break or have issues from time to time. And it looks bad and unprofessional when your website doesn't work for periods of time.