Once you have a name in mind, how do you know if the price is fair? I like to use namebio.com to compare the domain I’m thinking about buying with similar domains that have sold. You can enter the keyword and also use some advanced search features to see a list of names similar to yours, what they actually sold for, and when they sold. You can also research current domain sales on venues like GoDaddy Auctions and Afternic. Finally, Ron Jackson issues a weekly report on DN Journal that covers the top public sales of the week. You can use all these resources to help you price your domains correctly.
Let’s play this out with a real example. Say you’re familiar with the real estate market in Tempe, Ariz., and you have the opportunity to purchase tempeapartments.com for $200. This might be a good deal. Tempe has a lot of rental property; it’s  a competitive market; and there’s ample turnover in the apartment space because the city is home to a major university. Ask yourself:

The backlink profile of a recently-available domain is a double-edged sword. While some expired domains have been well cared for by their previous owners and have high-quality links from reputable websites, some contain quite questionable backlinks. The worst case scenario is that the domain was merely used as a link farm to strengthen a major project in a satellite domain network and has already been penalized by some search engines.
Hey, the possibilities are endless when it comes to domain flipping so do not think that all profitable domain names are already taken. At this time, almost 90 million .COM domains have been registered, so people tend to think that there are not many good domains left. That is not true since you still have the opportunity to incorporate two or three word target keywords.
Yes, buying existing domain names can be profitable too. Existing domains with a potential for profit can be found using Sedo. Make sure you pick domain names that have good traffic, backlinks and Google PageRank under 17 characters. Also, steer clear of existing domain names containing special characters or numbers because they are not likely to be sold.

Most of the website owners interested in an expired domain that has existing traffic, backlink and good SEO metrics. This kind of domain more likely gets buyer easily since it has a plus value for search engine optimization purpose. You can find high-quality expired domains that have SEO metrics by using BuycomDomain - The Expired Domain Search Tool for free, as seen in the picture below.
There is NO accurate way to predict the sale of digital assets – if someone wants it, they’ll buy it. For example, those wasting their money on useless .com’s (LLLL’s that have no rhyme or reason) will spend 3x more time and money optimizing their useless name as someone that buys ANY keyword loaded domain (regardless if a TLD or new one). But these individuals who are spending thousands on domains will eventually get stuck with these domains in favor of (you guessed it) the oft forgotten yet highly useful 1-3 keyword domains. Why? Study Google’s algorithm as I have for over a decade, and you’ll figure it out.
Length: This is pretty self-explanatory. Generally the shorter the domain name, the more valuable it is. This difference in value decreases exponentially as the name gets longer, though. For instance, the difference in price between 3 and 4 letter domains are significant, while the price difference between a 7 and 8 letter domain would usually be much less significant.