[owenm]

I would start with a business case - what are the benefits, is it going to generate revenue or reduce costs, when do the benefits start to be realised.

Then look at the cost in starting to develop what you need, and how you’re going to get started.

Are there existing COTS systems (e.g. SAP, Dynamics, Salesforce) that are extensible but can do 60% of the base functionality out of the box? Can you start by integrating two systems or using your low code platform to prove the concept? A couple of engineers/freelancers/external shop for a few months is a lot cheaper than hiring a whole development team… others in the thread have given you a reasonable estimate of that.

Think about what’s the MVP needed to start showing ROI. Maybe do a smaller business case for that.

Look at the payback period internally and ask what hurdle rate is needed to invest from your CFO.

[actionfromafar]

SAP does nothing out of the box, except maybe some parts may fall off and you'll find them under the couch later.