What features are required? what technologies are to be used? how many pages will there be? how fast do you want it up and running? What quality level of work do you want? -- can we get this done on time and within budget?
In short: It depends. But we're happy to give you an estimate.
Here is what I'm trying to say: You can ask anyone where a restaurant in your city is...but until you're clear about where it is and what kind of food do they serve..it's hard to tell. The same goes for website development...you need to clarify exactly what problem are trying to solve when building the site...and then let the developer guide you through the process.
The following questions will help get all those answers that you need:
Is it a business, blogging platform or an e-commerce storefront? This will help determine how much exposure the website needs to have and which technologies are needed to power the site.
Is this for tourists, locals or businesses? Knowing who will be visiting the website and using it regularly to find information is key in determining which features are needed.
Is your site mainly static pages with some dynamic content mixed in or filled with animations and video presentations? This will help determine how much time and money has to be invested into development.
You should have a clear breakdown of what needs to be included on each page as well as how visitors can navigate through the different sections of the website.
With websites, most times the client is looking for a minimum of 2-3 week turnaround time to get it live. Most complex websites can take 3-4 weeks or longer and can go up to 6-8 weeks or more depending on the project.
Do you want all your information saved in a database that can be easily modified, added or deleted by yourself?
What percentage of space will they take up on each page? Some websites only allow logos as ads while others dedicate full columns for them.
If it's going to take longer than expected..will you give us as many rounds of revisions as we need to get everything just right
This will include logo design, banner creation and so forth.
(Paypal, Authorize.net, Go-Payment)
I hope that helps. Website development is a tricky business.
Not only do you have to know what goes into designing and building one, but also try to figure out exactly what your client needs beforehand or else risk having them change their minds midway through the process which would lead to frustration on both sides.