The average American wedding around $30K, and of course, in major metropolitan areas is probably closer to $50K. That said, you can definitely do it for a lot cheaper...in fact I am building a business on planning events (including weddings) in the SF Bay Area for people who want a fantastic party but don't want to break the bank.
It's called La Divina Events and I am in the process of launching my website this month, but for now, you can check out my blog: http://ladivinaevents.blogspot.com/
I am currently working with a Spring 2008 bride who will be married in San Jose and has a budget of $10K. In 2007 I planned my own DW in Hawaii for about $13K which included 12 days in Hawaii (airfare, accomodations, car rental, etc.) as well as assisted another bride with her $6K DW in Montana for 300 guests. None of these events looked or felt low budget.
The three biggest factors in cost...the number of guests, the size of the bridal party and the time of year/date. If you can negotiate on any or all of those areas you can save thousands of dollars.