I am wondering whether there is a way (or some tool) that would enable anyone to forecast the cost of PPC campaign, but coming from end result: the number of visitors you want to buy...

Has anyone ever done that?

I will give you an example. Suppose you want to bring 10,000 visitors through keywords when someone searches for:
*company name being a web hosting company...

Is it even possible to instruct the system of that (I highly doubt), or does it mean you have to manually input hundreds of names yourself?

You can use cost estimator from Google Adwords,

yup..when you are creating a campaign on Google Adword, you will find a function called "Cost Estimator". this will calculate how much it generate from your budget..

But it isn't very accurate, maybe anyone know something techniques/services how to calculate it ?

Google AdWords provides a traffic estimator as a feature that can give you a sense of expected traffic. You should use this to determine your possible out of pocket costs and what you should expect to spend on a daily basis. The most important elements of a Google AdWords campaign include:

• Keyword choice. Generally speaking the more targeted, the better. You'll get less clicks but they will be people who specifically want your product or service.
• Advertising headline and text. The headline is the most important of these. Make sure it relates to the keywords you are bidding on - this will help keep the cost of your advert down.
• Display URL. The more relevant this appears to be to the keywords you're bidding on, the better.
• Landing page URL. This needs to be relevant to your keywords and advert. If you're bidding on Britney Spears then you shouldn't be sending people to a page about nuclear physics. It's not relevant and Google will penalize you by charging a lot more for your clicks.
• Per-click Budget. How much are you willing to pay per click? Determine what you are willing to pay per conversion (lead or purchase) and estimate how many visitors it will take for a single conversion.
• Daily Budget. The amount of money you are willing to spend in a 24 hour period. Keep in mind that if you're making money, it's okay to spend money.

These are just some of the basics associated with creating a successful AdWords campaign. The truth of the matter is that being truly successful with Google AdWords takes knowledge and experience. The more you work with pay per click advertising, the better results you will have.

Is there a way wherein you will definitely get positive results from the clicks that you are paying? I mean there are programs out there that are used to click on the ad but it is not a human which is interested about the website. I know that Google is blocking programs like this but there are still existing programs that do this.

And if you think carefully, Google is making money through this kind of scheme because they get profit from the clicks made by the program. How will I make sure that the clicks will be made by real people and not just bots?

A lot of people might assume that Google AdWords is extremely expensive but it may not be this way. By wisely and professionally managing your daily and weekly budgets you can receive a lot of clicks and web leads at affordable prices.

Do you think you can elaborate on your answer and provide some tips on how to get the most out of AdWords without spending an arm and a leg? If you can provide an example from your own experience, that would be very helpful.