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 generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By looking at the auction prices of coins with a similar condition (80), we can see that they have reached auction prices of up to 150 euros in previous sales. For example, at the auction on January 31, 2023, a coin with a condition of 85 sold for 150 euros.

3. Average Auction Price: The average auction price for this coin is 86.81 euros, which is also a good indicator of the expected value.

4. Starting Price and Average Starting Price: The current starting price is 75 euros, and the average starting price is 55.8 euros. This suggests that the market is willing to pay more than the starting price, especially considering the coin's condition.

5. Auction Trends: Since it has been auctioned 155 times and sold 134 times, there is good demand for this coin, which may increase its value.

Based on these factors, an estimated maximum purchase price for this coin could be between 120 and 150 euros, considering that the condition is good and there are precedents for auction prices in that range. A price of 130 euros could be a reasonable target for a bid.