Basement or above grade? Only a fool would post an open ended vague question for budgeting purposes. If you want a cheap basement go with block or normal poured concrete.
The low post count posters sound just like another nail bender accustomed to hiring cheap subs to do what he knows nothing about.
SF prices are worthless without checking out the history and performance of the installer. The sub can make or break a job, especially ICFs above grade, which terrify GCs because they do not understand the installation and advantages of the systems. You can always find a sub with no experience that buys cheap unsupported forms (no technical or installation support) from a form manufacturer that also makes foam meat trays for Walmart.
The problems usually come from the first timers or thase that cannot learn or read the installation and placement procedures and think ICFs are just a matter of dumping concrete, stripping forms and quickly covering up the mistakes.
I have seen many problems with SIPS after the GCs and unqualified subs are long gone or changed their names. Usually as a forensic engineer or an expert witness regarding moisture, mold or structural problems that that compromised the structural system.