There's also the real possibility the price increase is what is needed to pay for the additional staffing and tools to make AC better. For example, getting AC off of WinForms and onto Windows Presentation Foundation may not be easy. Also, there is the fact that AC is using SQL 2012 and 2017 has been released so it's time for another SQL upgrade. And those are just the things off the top off my head that need to get done.
JamesNT