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 (MBC+), indicating that it is in fairly good shape, but not the best possible condition (FDC).

2. Current Starting Price and Previous Prices: The current starting price is 1300 euros. In previous auctions, the average hammer price has been 1365.75 euros, suggesting that similar coins have reached prices close to this value.

3. Price Trends: By observing the hammer prices from previous auctions, it can be noted that coins with similar conditions have reached hammer prices that vary, but have occasionally exceeded 1500 euros, especially in conditions of 85 or higher.

4. Supply and Demand: The coin has been auctioned 67 times, with 56 sales, indicating good demand. However, the fact that there have been 11 occasions where it did not sell may indicate that the starting price is an important factor.

5. Future Projections: Since there are no auctions scheduled in the coming days, this could increase interest in the current coin, potentially leading to a higher hammer price.

Based on these factors, an estimated maximum purchase price could be between 1500 and 1700 euros, considering that the average hammer price has been 1365.75 euros and that there is potential for increased interest in the coin. Therefore, a reasonable maximum purchase price could be 1600 euros.