To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape.

2. Auction History:
- The coin has been auctioned 11 times and has sold on all occasions, suggesting there is consistent interest in this coin.
- The average hammer price in the past is 81.36 euros, which can serve as a good indicator of market value.

3. Previous Prices:
- In previous auctions, hammer prices have varied, but there are examples of hammer prices exceeding 100 euros, such as in the 2019 auction where it sold for 160 euros.
- The current starting price is 75 euros, which is slightly higher than the average starting price of 64.17 euros.

4. Trends:
- The overall trend seems to indicate that hammer prices have been increasing, especially for coins with similar conditions.

Based on this data, an estimated maximum purchase price could be set in a range between 100 and 130 euros, considering that the condition is good and there is a history of hammer prices supporting this estimate. A price of 120 euros could be a reasonable target, given that it has been reached in previous auctions and aligns with the interest in the coin.