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

1. Coin Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in relatively good shape. This suggests that its value should be above that of coins with lower conditions.

2. Previous Auction Prices: By observing the hammer prices of coins with a similar condition (80), we can see that they have reached hammer prices that vary, but some examples are:
- 2021-10-05: Hammer price of 55 (condition 80)
- 2021-04-20: Hammer price of 120 (condition 80)
- 2022-03-10: Hammer price of 115 (condition 80)
- 2023-12-13: Hammer price of 170 (condition 80)

3. Average Hammer Price: The average hammer price for this coin is 175.26 euros, which is also an important indicator.

4. Starting Price and Average Starting Price: The current starting price is 40 euros, and the average starting price in previous auctions is 147.2 euros.

5. Sales Trends: The coin has been auctioned 115 times, of which 99 have been successful sales. This indicates good demand and sustained interest in the coin.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and the average hammer price is 175.26 euros.

Therefore, a reasonable estimated maximum purchase price could be 200 euros.