The first thing you have to understand is Machine Learning projects are very risky. It is never possible to estimate the work hours required for the project. At the very beginning, there is no way to understand which direction to go. After elaborating an idea, we will set some paths and we will have to take a step on each of them. Even the first estimate on each option is a mini-research requiring a certain number of work hours.
Another thing to realize is you invest in the R&D process and not the end result. As opposed to traditional software development, having invested one-fifth of the total budget, you will not receive one-fifth of the final product. Instead, you will probably get proof if your hypothesis is right or wrong together with understanding, where to go next.
Usually, the first R&D step will last from 1 week up to 4 months. After that you may realize that you haven't been collecting your data properly and we can't use it to build a valid model. Sadly, one of our clients had to pay around $30,000 just to get this insight. Understandably, not every company is ready to invest this much in a 15-page report. It is only the ones who are really seeing the growth opportunities and the value that ML technologies can bring them.