To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in good shape. This is a positive factor that can increase its value.

2. Current Starting Price and Previous Prices: The current starting price is 1200 euros. In previous auctions, the final price has varied, but it has reached up to 3400 euros in the highest case (2024-03-14) for a coin with a condition of 85.

3. Average Hammer Price: The average hammer price for similar coins is 1978.46 euros, suggesting that the market value is above the starting price.

4. Sales Trends: The coin has been auctioned 14 times, of which 13 have sold. This indicates good demand and a history of successful sales.

5. Comparison with Previous Prices: In previous auctions, coins with similar condition (80) have had hammer prices ranging from 1500 to 1900 euros, which can serve as a reference.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 2000 to 2500 euros, considering that the condition is good and the sales history shows consistent interest in this coin.

Therefore, a reasonable maximum purchase price could be 2400 euros.