It depends upon the business you want to start because first, you need to describe the Budget of your small project. Some people will spend more on advertising to get awareness about the project so it depends on the projects and the advertising.
Have you ever seen where a company is about to start up a project and goes for a crowdfunding? Well, they always talk about hundreds of thousands and possibly millions of dollars. But since you said a small project, which I know, is likely to take place online, I would say make a budget of $5,000 to $10,000.