[Satam]

Maybe the limitations of the software arise from the fact that it's being sold at a price that's relatively too low? It sounds like it's very niche software with only a handful of users like you at most. With a small number of paying users, even if each one is paying thousands per month, the tool's team might be too underfunded for it to do much more than maintenance.

To do it in-house, you'll probably hire 2-3 engineers. You'll aim to have smart people who can self-manage, design, and who can intuit the business requirements. Your part-time duty will become to be the product's "CEO" of that whole thing.

So you'll end up paying at least €16000/mo (3x€6000) in salaries alone. Data access, storage and infrastructure will probably cost a bit too. How much are you spending now?