Why can the cost of a click for a keyword fluctuate? Let' say I have a kw bidded $1,00. Why can a click cost $0,06 and another $0,95? Is it due to clicks from different countries? Setting campaigns for different countries can lower costs? For example: Campaign 01: Location setting: USA/CA keyword: [training dogs] bidding: $1,50 Ad showing on google.com Campaign 02: Location setting: Denmark keyword: [training dogs] bidding: $0,50 Ad showing on google.dk Is it this one a realistic scenario?
Yes, you have to take into account that industries have different levels of competition in a variety of countries and even regions. For example, bidding on the term "buy rice" would cost a lot more in China than that of the UK. In your example USA & CA is likely to have many more competitors than Denmark which increases the CPC significantly. If you want me to expand on the answer with more details then just ask.
This means that instead of creating a single campaign with all the nations, I could create multiple campaigns settled on a single nation, and this should actually decrease the cost of the click. Thanks for your answer
I also noticed that to see the ad on google.co.uk, I always have to bid much more than elsewhere, whatever the niche. Why? Is because there are many sales in the UK?
Adwords has been fully established and used in the UK across every region, the problem is that many inexperienced users give it a go which pumps up the CPC. If you manage your account correctly then you will be able to reduce these CPC's over time.