In the NASA budget, -$230M is the "change from base year estimate" for the launch vehicle. In other words, the launch vehicle ended up being less than half the price of the initial budget estimate. (This is unusual; almost everything goes up from the initial budget.) Originally, congress mandated that Europa Clipper use the SLS to launch. But after vibration problems turned up with SLS, it would take $1 billion to redesign the Clipper. They say the SLS would have cost $1 billion for the launch vehicle. So I think the way the math works out is that SLS rocket cost much more than originally budgeted ($800M more?) and it would have cost another $1 billion to redesign Clipper. So abandoning SLS saved $230 million compared to the original budget but saved $2 billion compared to what SLS would have ended up costing.
Since SLS launches are now upwards of $2B per launch by some estimates, how does this math work? Wikipedia also suggests $2 billion saved.
https://en.wikipedia.org/wiki/Space_Launch_System#Europa_Cli...