Yeh, right, but it's down to a combination of targetting and SEO - and how many sites are up and running. Please bear in mind that I am learning about the website business, 3 months of poking about, but I am still a heap big novice that knows a bit about business in general.
I know a weeny bit about marketing, from my previous life. I can say that if you get a click, that is a 1 in 40 chance if everything is properly focused (ie. your site appeals to the target market), and it is a further 1 in 5 chance that the punter will buy something. That's how you get down to that 0.5% figure.
Now, in general, the heap of rubbish I have put out as websites are doing twice as good in those terms - slightly better than 1% click through to a "buy" decision. But I've recently put up a piece of trash -
Bowling A Hook Ball Round The Wicket - that is attracting attention organically, no SE submissions, and significant clicks - BUT NO SALES, despite the users spending over 5 min average on site.
I know I need to block out the irrelevant Adsense ads referring to golf, bowls and cricket. And I know the site needs more content. That's not the point.
The point is that, from where I stand, the tripe I usually turn out as "content" will normally hit that 1% "buy" mark - and my latest project is a failure from that aspect. But to get 0.5% buyers assumes you have TOTAL focus and interest, even if you are "preaching to the converted". Less than that just says you are not hitting the target ...