Let's say there are 3 types of domain: parked domain, in-use domains, monetized domains. Here's what I would do: Parked domain: I would offer no more than $50.

Let's say there are 3 types of domain: parked domain, in-use domains, monetized domains. Here's what I would do: Parked domain: I would offer no more than $50. Most parked, un-used domains are going to be parked forever. The chances being sold are very low, so you can use this advantage to really push down the price. Also, if the domain name is just the name of one of your project idea, you can always pick something else that its domain is available. In-used domain. At this part, it really depends. As jeffmould said, try looking up its search engine ranking and determine its value based on SEO. Monetized domain. Usually the owner of this kind of domains wants to sell at a relative high price. Do a little bit of research and estimate how much the site is making every month. Let's say it's generating $1000 ad revenue per month, anywhere between $5000-$10000 will be acceptable. To conclude, the golden rule is always offer your lowest expected price. Because the owner is 100% going to raise the price from what you say until you're both satisfied.