Its worth it if you plan on building and staying there for a while.
My friends in CS have 300-400 dollar electric bills in the summer. Mine has never gotten above $190 and that is usually in August. April - August ticks up froom 120 to its peak at 190. So if I'm saving at least 150 per month 6 months of the year, and 50 per month during the winter, that is a savings of 1200 per year.
My spray foam was 8000 over traditional insulation (we have roof and walls, everything is spray foam).
My A/C has extra dehumidifier, so temps are very low, if any humidity, and pretty close to true temps. I keep it at 73 when we're home. 76 when we're not, and 70 at night. I have blankets out for those who need them, and friends wives want them.
So ROI is 6.6 years.
I'd recommend spray foam to everyone. But I like a cold house and low electricity bills.