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+). This indicates that it is in relatively good shape, which can positively influence its value.

2. Auction History:
- The average hammer price for similar coins in the past is 52.88 euros.
- The condition of coins that have been sold in the past varies, but there are examples of coins with similar conditions that have sold for prices ranging from 30 to 200 euros, depending on the condition and demand at the time of the auction.

3. Starting and Hammer Prices:
- The current starting price is 25 euros, which is relatively low compared to the average hammer price.
- In previous auctions, coins with a condition of 80 have had hammer prices that varied, but some recent examples show hammer prices of 50 to 70 euros.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 40 to 70 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 60 and 80 euros, considering that the condition is good and that the price history suggests it could reach a higher value in a competitive auction.

Therefore, a reasonable maximum purchase price could be 70 euros.