To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape.

2. Auction History:
- The average hammer price for coins with a similar condition (80) has been approximately 44 euros in previous auctions.
- The hammer prices for coins with a condition of 80 have varied, with a range from 12 euros to 120 euros in past auctions.

3. Starting Price: The current starting price is 12 euros, which is relatively low compared to previous hammer prices.

4. Price Trends:
- In previous auctions, coins with a condition of 80 have had hammer prices ranging from 20 to 55 euros in the most recent auctions.
- The average hammer price of 38.5 euros also suggests that there is potential for the coin to reach a higher price.

Based on this data, an estimated maximum purchase price for this coin could be around 50-60 euros, considering that the condition is good and that the hammer price history supports this estimate. However, it is important to keep in mind that collector interest and competition in the auction can also influence the final price.