TL;DR: Building good software is difficult. Faster, better, cheaper for custom software is a myth. If you want good software, find an existing customizable solution for your business needs.
Imagine if car companies only sold custom-designed cars. While the result might get you from point A to point B, if you're constrained by a budget and timeline yet still expect a high-quality product, you will be sorely disappointed. It's no different with custom software solutions. The solution might perform all of the business requirements, but it's not going to be pretty. IT leaders are becoming more and more tech-savvy. They understand that great software is an iterative process. Version 2.0 will inevitably be better than version 1.0. A salesperson might promise to deliver a custom solution that is faster, better, and cheaper than the competitors, but the harsh reality is that it is a myth. These three reasons will lead to a problematic or failed implementation. All hope is not lost, though! Unless your enterprise is in a very niche industry, there is likely a product that meets 90% of your requirements.
It turns out that the unique requirement for the car you wanted was the interior and exterior colors to be red. You realize that for your budget and timeline, you can get a Toyota Camry. You'll pay an upcharge for the color customization, but it is a highly reliable car. The initial cost is known, and maintenance is reasonably predictable. Everyone is happy. I don't mean to continue repeating the analogy, but I am often shocked by IT leaders' resistance to go with a proven solution. When purchasing a scalable software product, you're only paying for the company's marginal cost to make a profit. With a scalable solution, you can indeed get faster, better, cheaper.
Nowadays, with software-as-a-service, you can usually try before you buy or not get locked into long-term contracts. SaaS substantially lowers the risk that your technology will be outdated in a few years or worse, introduce technical debt to your organization that ends up costing multiples more to maintain over the lifetime of your custom solution.
No one understands your business as you do. Unique requirements can potentially still cause some barriers when customizing SaaS. Setting clear communication guidelines and providing sufficient time from knowledge experts is a must. It's also essential the vendors provide excellent service. If any critical business issue is found, you need a fast response time to avoid any negative impact.
Also, do not select silos. Modern software needs to be able to communicate with other solutions securely, ideally through a REST API. A solution can be a perfect fit for your requirements, but if it locks in your data, that's a hard pass.
In other words, make sure you have a good mechanic and don't buy a car that only runs on CNG. You're still going to have to work through issues, but as long as you plan and are aware of what to look for, it will be a pleasant journey.