I decided to have a look at the link from OP's article to see why the claimed cost ($1600) was so different to yours. Some of it was fairly reasonable...
- Race fee $86.40
- Extra food/coffee: $79.90
- Extra laundry: $25
- Transportation & lodging: $95
... some of it was very individual or easily avoidable on a budget...
- Gym membership: $130.50
- Pet car: $50
- Sports massages: $210
- Post-race celebrations: $163.46
... and the rest just seemed a bit excessive/unnecessary...
- Gear: $578.80
- "Running fuel": $19.90