It's hard to work out the actual cost of each SLS. Especially when you're trying to take development costs into account. The lowest sensible estimate I've seen

It's hard to work out the actual cost of each SLS. Especially when you're trying to take development costs into account. The lowest sensible estimate I've seen is $3 billion, but if you amortise development costs over ten launches it could be higher than $5 billion a launch. A Falcon Heavy in expendable mode can be had for $150 million, and NASA paid no development costs. So, between 20 and 35ish times more expensive (assuming nothing much more goes wrong for SLS), and Falcon Heavy is already flying.