http://feinternational.com/buy-a-website/#tabs-3
http://www.webrokr.com/soldsites.php
For sites/apps with steady traffic & earnings, the general rule of thumb for calculating valuation has been multiples of monthly net profit:
* 2002-2004: 3 to 6 x monthly net
* 2005-2012: 10 x monthly net
* 2012-2014: 20 x monthly net
* 2014: 30 x monthly net
So to flip a site for > $200k, you need to be doing approx > $7k/month.
At time of writing (August is usually quiet) there are around 300 brokered,web-based businesses for sale between $20k and $2M.
Averages are severely deceiving but If you were to look at average multiples alone you would find a typical range between 1.8 and 3.7x annual net profit.
It's not the sexiest process, or the highest valuations, but if you're looking to exit for 5-to-6 figures, you might be able to find a buyer there easily.