To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current starting price: 60 euros.
2. Coin condition: 70 (MBC-), indicating good condition, although not the best.
3. Auction history:
- In 2019, the coin was auctioned with a starting price of 60 euros and sold for 60 euros, indicating that the starting price was appropriate for its condition.
- In 2014, it was auctioned with starting prices of 20 and 15 euros, and sold for 25 euros in both cases, suggesting that interest in the coin has increased over time.

4. Average hammer price: 36.67 euros, which is lower than the current starting price, but may reflect an increase in demand or in the coin's condition.

5. Auction trends: The coin has been sold every time it has been auctioned, indicating consistent interest.

Given that the coin is in good condition and has maintained its value in previous auctions, an estimated maximum purchase price could be slightly higher than the current starting price, but not too much, to avoid overpaying.

Estimated maximum purchase price: 80 euros.

This price reflects a moderate increase over the starting price, considering the good condition and auction history.