Every domain name reseller needs to check out this website value calculator, found at this link: http://www.websitevaluecalculator.com/. Here you can enter the URL of any legitimate website and find out a ballpark value of how much it is worth. If you are happy about the value estimate that is given after entering your URL, they will give you HTML code for a banner that states the value of your website underneath a close up picture of George Washington from the dollar bill.
This website is even fun to use right after you complete the steps of a cheap domain name registration. This will give you a starting mark of what your website was worth in the beginning. The site value calculator creates an estimate by looking at the traffic rating, Google page rank and the average amount of back links that are found from the most popular search engines. That being said every domain name reseller has to check this useful tool out. They will also give you a short website analysis readout about how to optimize your profit potential.