06 Jun 12
07 Mar 14 5:25 pm
In the end a domain name on it's own wont wont determine who is ranked first, however it may give a few brownie points.
When a user is looking at the domains however, an exact match will be more likely to grab their attention and give the impression of more authority on the matter. ~ Who sells the best tea? A tea store or a supermarket?Long Answer
I find that time is often a more important factor than domain name.
Matt Cutts from Google "claims" that a domain name doesn't affect SEO rankings much anymore, though I'm not so sure I believe him.
If you're promoting your own products, I would buy the domain to prevent others taking it.
If you're promoting someone elses products, I would check that there is nothing in the affiliate terms and conditions preventing you from using their product name in a domain name and also consider possible trademarks.
Overall it is best to have a large authority site with many natural visitors and lots of good content.
However your statement "Of course i can't buy new domain name every time i pick products to promote" may not exactly be true.
Having a very targeted small website can also sometimes get you many sales if the niche isn't too competitive. I've seen Google many times give preference to small targeted sites over huge authority sites when the small site is very targeted with good SEO. The payouts can be quite good. As long as you made $10 in sales per domain per year you're really at no loss.