All ERP systems (like SAP) are sold the same way: people in suits who don't know much about the internal workings of the actual software sit in boardrooms with executives and show them powerpoint slides of the reports that their ERP system will provide them, and none of the executives worry about the fact that (a) the software is expensive to install and even more expensive to customize - with consultants bringing in up to $200 per hour sometimes, (b) you have to adapt your business processes to the ERP system, not the other way around, unless you want to spend even more $$$, (c) any customization you do make has a good chance of being broken when you upgrade to the new version, (d) the extra data entry work that has to be done to actually get real data into the system to generate those reports probably costs more than any savings you'll realize as a result of having all that data.
I maintain an in-house ERP system written in C# running on SQL server for a small business of about 150 employees, but we're growing fast. I only spend about half my time on the development and tweaking of this system, so the only thing it costs is two VMs and half my salary. (Note that this is separate from the accounting system). There's absolutely zero licensing costs. The software is tailored to the way we do business, not the other way around. It collects data directly from the diverse manufacturing machines on the plant floor through interfaces that I can write, control, and maintain, and it does this without any manual data entry on the part of the users. Its unit test coverage is over 90%, so we can push out changes and updates without fear of breaking existing features, and I can respond to new feature requests sometimes within hours or even minutes. It tracks employee time, project management, design, purchasing, production, inventory, shipping, maintenance and costing all in a single integrated place.
Companies buy off-the-shelf ERP systems so they don't have to manage people like me, but they really end up paying through the nose for it.