The easiest way to answer this question is to put it into a context. How much does a house cost?
If you only need four walls, a door, a window and a roof, and you're planning to purchase and assemble the materials yourself, you can do it on the cheap. If you're not handy with the tools used, it still won't cost much in labor even if you have a professional build your small house for you.
What if you require a little larger structure? How many rooms do you need? Do you want to use a ready-made plan, or a custom design? Do you want your guests to have full access to all of your house, or do you want to separate public and private areas? As the project becomes more complex, there is more to consider, more to build and more things that need to function together.
What if the house is not for personal use, but is a business structure? Then you have another set of challenges. What if you have a business that exists in several locations? And/or you need employees to access and control various parts of the structure?
In this website analogy, the basic four walls and roof is like an online brochure. It is the simplest of websites with some information about your product or service and a way for people to contact you by way of some combination of address, phone and email.
The next level of website has more information and some interactive elements that enhance the user experience. It performs some function beyond merely conveying information.
The third represents a larger, perhaps enterprise level website, where information changes and updates often. It is likely database driven (could be e-commerce, product pricing sheets, community elements, a blog, etc), and the content itself may be accessible by different levels of website editors, as well as varying customer level access.
One advantage that websites have over houses is that it's pretty easy to add onto the structure while maintaining the original appearance. Websites can expand over time easier than houses (keeping in mind that poor planning can be detrimental to a project in any industry), and thus be cost-effective by assembling only the parts needed at this point in time. "Build-as-you-go" is an effective web development strategy as long as there is a clear goal and plan for growth.
How much should I budget?
How much you have to spend will determine the growth rate of your website. While a database driven e-commerce website can easily set you back 8-10 grand, for a small or start-up business, depending on your product, it may not be necessary to outlay that kind of cash at the inception. You can get started with a deposit of just a few hundred dollars to begin work, a simple template with a few pages and a growth plan. As you work with your web developer over the span of a few months, your website can start bringing in customers — thus, income — to help fund future growth.
This is the kind of website growth plan that I frequently recommend to small businesses.
1. Go live as soon as you can with what your budget will allow.
2. Get your product or service information out there with a way for new customers to contact you.
3. Follow your growth plan to develop your website from there.
Websites cost varying amounts depending on functionality. Your budget will determine the growth rate. Your website plan will keep you on track as you work toward your goals. By just doing one manageable thing at a time, you'd be surprised at how quickly and affordably you can develop a strong presence on the web.