Does downtime really cost only $100 per day? How was it calculated? How much does your business make? It would seem it should make more than 365 * $100 = $36,500 to be able to be in a position to hire people in the first place.
Database downtime would potentially:
1) Break trust with customers.
2) Take away focus from your engs for a day or more which is also a cost. If an eng costs $200 per day for example, and you have 4 engs involved with, it's already a cost of $800, not to mention increase of odds of stress and burn out. And in US engs would cost of course much more than that, I was just picking a more favourable sum.
3) If it's a database that breaks, it's likely to cause further damages due to issues with data which might take indefinite time to fix.
Overall in most businesses it would seem a no brainer to pay $2000 a year to have high availability and avoid any odds of a database breaking. It's very little compared to what you pay your engineers.
