To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the current condition of the coin (80, MBC+) and previous auction prices.

1. Condition: The coin has a condition of 80 (MBC+), indicating that it is in relatively good shape. This suggests that its price should be in the upper range of previous auction prices for coins with similar conditions.

2. Previous auction prices: By looking at the auction prices of coins with similar conditions (80 and 75), we can see that:
- In 2022, a coin with a condition of 80 was auctioned for 160 euros.
- In 2023, another coin with a condition of 80 was auctioned for 190 euros.
- In 2022, a coin with a condition of 75 was auctioned for 151 euros.

3. Average auction price: The average auction price for all auctions is 166.88 euros, which can also serve as a reference.

4. Starting price: The starting price of the current auction is 140 euros, which is reasonable given the price history.

Based on this data, an estimated maximum purchase price could be between 180 and 200 euros, considering that the condition is good and that previous auction prices for similar conditions have reached those levels.

Therefore, an estimated maximum purchase price for this coin could be 200 euros.