Responses (1)
Much code nowadays is open source, or you plug into someone else's interface (such as secure login to paypal) through an api; with some knowledge & fiddling, it's theoretically possible to set up the framework on a nigh zero budget (acquire a cheap domain and run the server on your home pc / laptop).
The big difference is in the userbase and data. Getting people to use your product is monumentally difficult, as your service would have to offer some added functionality as well as sufficient reliability (specifically, many of your competitor's features) for any sort of traction. As for the data, it might require collection skills (such as google crawling the web constantly with some ingenious proprietary algorithms), or the userbase providing it. Ddg plugs into bing's api and just adds a layer of security, which some say wouldn't be viable once it gets sufficiently popular.
There isn't a direct estimate of the money, since one could go a long way with a small dedicated team, whereas the bribes & wrist twisting are carried out in the shadows. What's certain is that as a small start up with few resources (less than millions, I'd estimate), you'd be coerced to selling out (then disassembled & assimilated) by a tech giant - check out all the list of company acquisitions made by alphabet, and what they did with them. Most likely, converted to a paid service and retired.