If you're operating a company with real customers and real cash flow at any kind of real scale, and you suffer a serious breach, figure $50,000-$60,000 is table stakes for getting that breach resolved.
The intuition you need, to price these things out, is that once an attacker obtains unexpected unauthorized access to a system, the very next thing they do (and, in this case, the very next thing they tried to do --- much to Keys chagrin) is extend and persist access. Which means that if you're resolving a breach, you have to re-assess every system that the attackers got unexpected access to and verify that they didn't (a) implant something that will restore access in the future or (b) uncover some latent vulnerability that would allow them to do that.
Nobody reliably assesses internal systems (those systems you get unexpected access to once you successfully obtain unauthorized access). Nobody. An attacker gets behind the login prompt on a CMS you've deployed? You probably need to re-assess the whole CMS, because a big chunk of your security for that CMS probably relied on the idea that attackers don't know and can't reach all the URL endpoints behind the login prompt. The attacker gets code execution somehow? Now they're on your internal network, and the same goes for every system on the internal network.
It adds up fast. And your insurance company will (a) demand that you pay it, and (b) shortlist your DFIR vendors for you.
Not fun times.