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

1. Current Condition: The coin has a grade of 80 (MS+), indicating that it is in relatively good condition. This suggests that its value should be above that of coins in worse conditions.

2. Auction History: By looking at previous hammer prices for coins with similar grades, we can see that:
- In past auctions, coins with a grade of 80 have reached hammer prices of up to 180 euros (as seen in the auction on 2020-02-13).
- There are also examples of coins with a grade of 85 that have sold for 260 euros (auction on 2022-06-01).

3. Average Hammer Price: The average hammer price for this coin is 149.5 euros, providing a good reference point.

4. Starting Price and Estimated Price: The starting price is 75 euros, and the average starting price is 76.21 euros. This indicates that the market is willing to accept starting prices in this range, but the hammer price is usually significantly higher.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of being higher, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 180 and 220 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

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