If you prefer a more traditional URL, you'll need to purchase one from the likes of GoDaddy or Namecheap. Domain name pricing can range from extremely cheap to extremely expensive, depending on whether or not domain squatters are looking to flip a valuable piece of online real estate. You'll want to get something short but evocative and catchy, and depending on what you do, you may find that many of your first choices are taken by either other legit domains, or by squatters who've scooped up the names as an investment. For more, please read How to Register a Domain Name.
The selection below should be plenty to get you started. Read the blurbs and then click through to the linked reviews to find the one that best suits your needs. And don't hesitate to chime in below in the comments section to report your experience with a site builder or praise one that's not included. For more advice and alternatives to DIY website building, check out our primer, How to Create a Website.
While the the best of them offer surprising amounts of flexibility, they also impose stringent enough restrictions to page design that you shouldn't be able to create a really bad looking site using one of these services. Typically you can get a Mysite.servicename.com style-url with no commerce abilities for free from one of these services; you have to pay extra for a better URL and the ability to sell. One issue to consider is that if you eventually outgrow one of these services, it can be hard to export your site to a full scale advanced web hosting like Dreamhost or Hostgator. If you know that's where you are eventually going, it may be better to skip the sitebuilder step. Marketplace Template: Build and launch an online marketplace in less than 2.5 hours