Then your renewal comes up and you’ve already spent another million in salaries and bespoke shit to make it work for you and the sales guy hits you with 500k again because you’re in too deep.
Cisco was legendary around here (20+ years ago when I was around networking). They would win almost every tender, often with quotes below cost if that is what it took. And everyone in the know knew you would be paying much, much more over the next few years with support costs, renewals, etc. The first hit is free.