A friend of mine has quite a few car websites. He sold one a few years ago for around £10,000 ($15,000) and worked with the company to develop this and a numberr of websites. A year later he was made redundant.

All through this time he was working on developing his other sites. He turned down an offer for around £20,000 (£30,000) for his business , when he was struggling to make any real money. He was tempted, but turned it down. He now makes around £3,000 ($4,500) a month and is being wooed by the car companies, which includes flights to places, such as Portugal, to test drive a new car.

He makes his money from mostly Google Ads. I personally believe he could make 10 times what he does from the mainstream advertisers, but at present he is happy and in a way by retaining his independance he is increasing the value of site every month. At some point in the future he should be able to sell his domains for may times the offer or work out a deal with a marketing business to build a real income.

So I agree the value of a website should in many cases take into account its potential.

However if you are buying a website you should be arguing that this is not so.