how to evaluate the value of website?

1. Daily Unique Visitors
In my view, this is the single most important factor in determining the value of a site. Even in a low paying niche, if you’ve got the traffic, you can make a killing. Take this site for example: http://dogbreedinfo.com/ – with over 2.5 million unique visits per month, they generate mucho money (something like $600/day in AdSense revenue alone).
At a very deep level, daily unique visitors gives you a sense of the value of your site in the eyes of your potential customers. Contrast this with various factors such as Google PageRank which give very little indication of the value of your site in the eyes of potential customers, but rather reflects (poorly in my view) the value of your site in the eyes of other websites.

2. Average Daily Profit
Forget gross revenue. Who wants a website that generate $2000 in revenue but spends $2100 in advertising and maintenance expense. Revenue is very seductive, and it is normally what gets listed on sites like SitePoint. But before you buy a site, make sure you know both the expenses and the revenue…and their difference.
The reason I don’t put Daily Profit above unique visitors is that daily profit is a variable that almost always relies heavily on unique visitors. Plus, Daily Profit is a variable that depends to a large degree on the manager of a site. If a website is currently being undermonetized, but has great unique visitor stats, then you’ve got a great opportunity to jump in and maximize profits.

3. Quality of Content
If the website is informational, then ask yourself how original the information is. Is the information considered authoritive or does it at least have the potential of becoming authoritive? So much of the content on the web is junk, so when you find that rare gem of a site with genuinely useful and unique content, it might be worth paying a premium, even if various other factors are lacking.
One thing to consider, however, is whether the content ages quickly or not. If a site produces qualityvideo tutorials on topics in fast moving niches like SEO, the critical question to ask is whether the content is timeless, or whether it will be irrelevant in 2-3 years. Not all content needs to be timeless. If you’re up for the challenge of producing a steady stream of relevant content, go for it, but just make sure you know what you’re getting into.

4. Backlinks from other sites
In my view, backlinks and their associated metrics (i.e. PageRank) tend to be way overvalued on the web. Now, you can take advantage of this fact and try to sell sites on these metrics alone. But in the end, PageRank should not be the only reason you buy a site. I’ve seen shoddy five page sites with PR6 sell on SitePoint for $2000. The fact of the matter is that most of these sites have been artificially pumped up and then sold off. Beware of this strategy.
One way to identify whether you’re being conned or not is to go to www.live.com and do a “link:www.domain.com” search. The reason I prefer Live.com at the moment is that it lists backlinks by domain, so you can get a good picture of the total number of domains (as opposed to pages) linking to a site. Why does this matter? Because diversity in backlinks means you probably won’t lose your PageRank if one or two sites pull their links.
In the end, backlinks matter, but in my view they only matter at a domain level. The best tools on the web for checking a site’s backlink value are Live.com, Yahoo SiteExplorer and SEOMoz PageStrength.

5. Visual aesthetics / Site Layout & Design
Content is king, or so they say. But what most people on the web ignore is a great site design. As we all know from the sale of cars, humans often judge a product by how it looks and how easy it is to use. Find a beautiful but functional site, and you’re half-way there. Personally, I think paying for a nice site design these days is way undervalued. The reason? Well, site design is quantitative and it doesn’t result in profits all on its own. But a good design will help you keep your customers, and that, as they say, is priceless.

6. What the Niche, dude?!
The topic of your site has consequences. Are you passionate about the topic? Will the topic keep you focused and consistently dedicated to the site? Does the niche have an audience? Has the niche been proven to be profitable in the past? Is the niche oversaturated or undersaturated? How easy will it be to develop product or content for the niche? How easy will it be to acquire customers and/or readers in the niche? These are all questions that determine the value of a site not only from a objective standpoint, but also the value relative to you as the owner. Which brings up a key point – value is in the eye of the beholder – if you like losing money, then hey, there’s lots of sites out there with lots of value! Of course no one likes losing money! So if you want to make money, make sure you have a sense of how you want to make it, and how you want to spend your time doing so.

7. The Intangibles
Things that are priceless these days include:
Age of domain – The older the better.
Quality of domain – Memorable and/or short but keyword rich domains are best. In general, stick with .com
Age of content – Again, the older the better in cases of timeless content
Strong Search Phrases – how much of the traffic is coming through targeted search phrase? You’re not taking advantage of the global market place, if the global marketplace can’t find you.