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

1. Current Condition: The coin has a condition rating of 80 (MBC+), 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 similar coins in the past is 35.35 euros.
- The last auction for a coin with a similar condition (80) had a hammer price of 55 euros.
- Overall, hammer prices have varied, but there are examples of auctions reaching up to 70 euros for similar conditions.

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

4. Sales Trends: The coin has been sold in 24 out of 28 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 55 to 70 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 65 euros.