This just seems to be standard business case analysis between in house vs buying a product. In general management won't really care about the technical pros and cons, all they will care about is the financial pros and cons. So your starting analysis should be:
Is it cheaper to produce it in house or is it cheaper to buy a well supported package in order to meet the given technical requirements?
And you need to be brutally honest in your cost analysis. EG my professional time is worth about $1000/day, but I doubt I could produce a product to the quality levels (and more importantly - correctness!!) of Sepasoft before I hit the Sepasoft purchase price. And that's not including ongoing support and documentation etc.
OTOH in a past life I did build a custom OEE system for a manufacturer. But that was because it had to slot into a combined PLC/SQL server based system which had no possibility of plugging in a separate commercial package. And while the system worked, it was very limited in its functionality.
OTTH (third) this equation changes if you are in the business of building custom software solutions that will be sold to clients (EG you are a competitor to Sepasoft). But from the way your question is phrased I doubt that this is the case.