Weird cost estimate result - mathvista gpt-4o

<img width="773" alt="Image" src="https://github.com/user-attachments/assets/cc869595-bf3e-43e1-9305-4e8b3b27b134" />

The two yellow dots in the centre:
- The left is 4o, and the right is 4o-mini
- This suggests that 4o-mini is much cheaper than 4o for this particular benchmark. Seems worth investigating why