Ditto the above. Cheap and professional are usually not found together. Reasonably priced, customer service and a great website that performs well are things that go well with professional. Some things to stay away from are do-it-yourself templates and foreign service websites.
I recommend reading this article to get started. It outlines what to look for in web services, web designers and has a few links to further articles about working with your web designer.The Clueless Business Owner`s Guide to Going Online
Depending on your needs (number of pages, graphics, cart system, other) you can expect to pay between $400-$2500+ for a site that looks amazing and functions well.
Let me know if I can help,