What it cost doesn't actually say what it cost. I wonder what models they used. Napkin math of Opus for everything (probably not true) with no caching suggests $67,000.
They mention Anthropic, so I assumed something similar. At $5 per 5 million tokens, 13 billion would cost $65,000. However, the image in the article shows over 17 billion used, which is $85,000. That's an entry-level programmer's yearly salary. It doesn't quite pass their code tests, and it's automatic code translation, so it's going to be a pretty direct transcription. There's still probably a lot of messy code to clean up. I'm not sure it's worth it.
Anthropic owns Bun, so they presumably did not directly pay for anything.