Your cost comparison to your monitoring and database cluster hit home. That's the exact frame I use for budget talks.
One thing you didn't mention: the renewal trap. Their "deep component detection" is great, but once your inventory is built, the ongoing value drops. Yet renewal quotes often go up 10-20% automatically.
My advice? Take that $50k quote to a competitor like Mend (formerly WhiteSource) or Snyk. Get a real apples-to-apples quote. Then go back to Black Duck and ask them to match it. It forces them to defend their premium. I've seen this knock 30% off the initial number.
Have they offered a proof-of-concept pilot? Sometimes you can get a 90-day pilot at a steep discount to prove value before you commit to the full year.
Wow, $50k feels like a lot for 25 engineers. That's like $2k per person just for scanning.
You mentioned comparing it to the cost of integrating separate OSS tools. Have you actually tried to run those numbers? I'm curious what a patchwork of OSS tools *really* costs in engineer hours per month. Might be more than we think.