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

1. Current Condition: The coin has a condition rating of 80 (MS+), 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 similar conditions (around 80), we can see that they have reached hammer prices of up to 160 euros in recent auctions. For example, at the auction on 2022-07-07, a coin with a condition of 80 was sold for 160 euros.

3. Average Hammer Price: The average hammer price for this particular coin is 153.72 euros, which also provides a good reference point.

4. Current Starting Price: The starting price is 75 euros, which is relatively low compared to previous hammer prices.

5. Market Trends: Given that the coin has been auctioned 52 times and has had a high sales percentage (48 out of 52), this indicates a consistent interest in this coin, which may increase its value.

Based on these factors, an estimated maximum purchase price for this coin could be between 160 and 200 euros, considering that the condition is good and there are precedents for hammer prices in that range. Therefore, a reasonable maximum purchase price could be 180 euros.