Below you can see a brief treatment I wrote up with reference images for the look you mentioned on the phone.
Here are two ballpark budgets to pull off the piece:
Option #1: Interview & B-Roll: $4,725
- Trimmed this down quite a bit to get it close to 50% of the overall budget, with the idea of doing a second story.
Option: #2: Interview & Underwater B-Roll: $8,475
You can click on the image to download the full treatment.