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

1. Current Condition: The coin has a condition of 80 (VF+). This is an important factor, as coins in better condition tend to reach higher prices.

2. Previous Auction Prices: By looking at the auction prices of coins with similar conditions (80 and 85), we can see that:
- In 2020, a coin with a condition of 80 was auctioned for 1600 euros.
- In 2013, another coin with a condition of 80 was auctioned for 2700 euros.
- In 2022, a coin with a condition of 95 was auctioned for 6000 euros, indicating that a higher condition can significantly increase the price.

3. Average Auction Price: The average auction price for this coin is 2433.73 euros, which can also serve as a reference.

4. Auction Trends: The coin has been auctioned 13 times, of which 12 have sold. This indicates good demand and consistent interest in the coin.

5. Starting Price: The current starting price is 1800 euros, which is a reasonable starting point.

Based on these factors, an estimated maximum purchase price could be between 2500 and 3000 euros, considering that the condition is a key factor and that the average auction price is 2433.73 euros. This also takes into account the price trends in previous auctions and the demand for the coin.

Therefore, a reasonable maximum purchase price could be approximately 2800 euros.