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

1. Current Condition: The coin has a condition of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for coins with a similar condition (80) in the past has been approximately 35-50 euros.
- In previous auctions, coins with a condition of 80 have reached hammer prices of up to 35 euros (as in the auction on 2020-02-13) and 50 euros (as in the auction on 2022-04-28).

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, which is below the average starting price of 34.57 euros. This suggests that there is potential for the hammer price to be higher.

4. Sales Trends: The coin has been sold in 35 out of 47 auctions, indicating good demand.

5. Comparison with Previous Prices: In previous auctions, the highest hammer price for coins with a similar condition has been 110 euros (although this was for a condition of 85).

Based on these factors, an estimated maximum purchase price for this coin could be between 50 and 70 euros, considering that the condition is good and the price history suggests it could reach a higher price at auction.

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