To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the current condition of the coin (70, MBC-) and the hammer prices of coins with similar conditions in previous auctions.

1. Condition of the coin: The coin has a condition of 70 (MBC-). This indicates that it is in an acceptable state, but not in the best condition.

2. Previous hammer prices: By observing the hammer prices of coins with similar conditions (70 and 75), we can see that:
- In 2020, a coin with a condition of 70 was sold for 45 euros.
- In 2022, another coin with a condition of 70 was sold for 60 euros.
- In 2019, a coin with a condition of 85 was sold for 85 euros, indicating that the price can increase significantly with better condition.

3. Price trends: The average hammer price for all auctions of this coin is 73.54 euros. This suggests that, in general, buyers are willing to pay around this price.

4. Maximum price estimation: Given that the condition of the coin is 70, and considering that the highest hammer price for a similar condition was 60 euros, we can estimate that a reasonable maximum purchase price could be in the range of 60 to 80 euros, taking into account that the average hammer price is 73.54 euros.

Therefore, an estimated maximum purchase price for this coin could be 80 euros. This allows for a margin for competition in the auction, given that there is interest in the coin and it has been successfully auctioned in the past.