On prem is easy if you are willing to pay 100K a year. Once 6 figures come into play, any SaaS company would be willing to do on-prem. I find that those complaining about on-prem are mostly small business customers that are more trouble than they are worth. Serious B2B companies won't blink at those prices.
I've rejected plenty of >100k a year proposals because there wasn't an on-premises alternative. (And also another batch because despite being willing to pay yearly for upgrades and support, there wasn't an option of retaining the license in perpetuity.)
SaaS and on-prem software are very different in how they are developed and require different expertise. Even if you would pay a SaaS company enough so they will be willing to adapt their SaaS to on-prem it will be a mediocre product.
