How much do websites cost to build?
TL:DR There is a huge range in total cost for the development. There is no way to tell without getting all the details down on paper and quoted. Projects that are easy to explain are hard to code and projects that are hard to explain are easy to code.
At least three or four times a week, someone asks me how much their idea is to build. They want to build a marketplace for selling handcrafted goods or a barter network for hobbyists or the next best social network. They call me up, speaking with a secretive tone about the concept, and explain for 5 to 10 minutes about their idea. At the end of their explanation, they almost always ask, "how much do you think it would be to build this?" My answer is almost always, "I'm not sure, I need to take these items back to my development team and do the research required to create an accurate estimate."
Frequently, my web development and project management services bump up against construction project management skills. The terms "construction worker" or "contractor" refers to a type of labor who builds something. Even though our finished projects aren't tangible, many of the skills are exactly the same. We bid projects, we plan out projects on an architectural level, and we have to stay within a specific budget. There are many, many more crossovers, but the basic concepts are the same.
I use this comparison because the cost for building a very complex website with many moving parts, users, and functions is very similar to building a skyscraper. The amount of effort that is required to build a skyscraper is monumental. Additionally, there are many people who call themselves contractors that are not up to the task of building a skyscraper. However, describing a skyscraper is very easy. It is a huge building with many floors that stretches into the sky, They provide office space or living space. It took me approximately 10 seconds to describe a skyscraper, but it may take 10 years to plan and build one. The exact same thing happens with a complex website.
One of my favorite phrases to explain how this works the client is, "projects that are easy to explain are hard to code and projects that are hard to explain are easy to code." Without fail, this phrase has been extremely helpful. Let me give you an example; eBay is a website where users can post their items for sale in an auction format. Other users can come online and bid for that item until the timer runs out. Whoever has been the most will pay online for the item and the original posting user will ship that item to them directly. I just described to you the 17th most popular website on the entire Internet. Unfortunately, I can't even begin to estimate how many development hours have gone into developing eBay.com
Now for the fun part, I'm going to explain the opposite. I'm going to build a website that has a complete listing of every square root from numbers 1 to 1 million. Just for fun, I'm going to highlight the primes. Personally, this makes my head hurt just to think about. However, a competent programmer can get this done in about an hour or two. Computers do things that are very complex to think about very very quickly, especially math.
In conclusion, the best thing you can do for your developing project today is to plan out all the features and functionality that you expect to have. Spare no detail. Whether your project is a skyscraper or Sandcastle, the biggest favor you can do for yourself today is to write down what you want and think through all your features. Once you've done this, it will be very easy for any developer to give you an honest and accurate estimate for cost and total time needed to deliver.