how much to pay to build a website and whats the rule for the price of building website?

Way too many variables to generate a blanket quote.
Do you already have an established visual identity?
What will be the features of the site?
How heavy in content will the site be?
Do you need help acquiring the domain and hosting?
How many rounds of edits do you anticipate?

Do you want to update your content?
What quality of code do you want?
How dynamic will the backend / frontend be?
How long are you planning on the project taking?

PupnTaco is right, there are way too many variables. Every freelance designer or designhouse has a rubric with which they interview YOU, to best determine your needs – and based on those needs (and wants) you are given a quote. Something as simple as (are you an individual, nonprofit, small business, corporation) will determine the pay scale. And so on.

The general rule of thumb for build websites is if its less than $150, don’t do it. Usually for the first page (with or without CMS), people charge about $300+. Other than that the prices go up for image editing, logo design, content management,etc.

I charge by the hour, (don’t know anyone who charges by the page anymore). So basically it boils down, as other have said, the requirements of the project dictate the amount of time, the time dictates the amount charged.

Small projects, at my rate, run around 1500–2500 on the low side. Larger projects have run between 7000 – 12,000.

It all really boils down to time, for me anyway. I don’t vary my rate for database design or scripting, etc. It is all one rate per hour.

Charging by the page just encourages the client to put everything on one page, which is bad information architecture.

A web site with no dynamic content and no complex requirements will probably run around $1000—$1500 before the costs of hosting, and it only goes up from there.