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

1. Current Condition: The coin has a condition rating of 30 (BC+), indicating that it is not in very good shape. This generally negatively affects the hammer price.

2. Auction History:
- The average hammer price for similar coins in the past is 76.63 euros.
- Previous hammer prices for this coin have varied, with a maximum price of 120 euros in the most recent auction (2024) and a minimum of 18 euros in 2016.
- Most hammer prices fall within the range of 50 to 85 euros.

3. Starting Price and Average Starting Price: The current starting price is 25 euros, and the average starting price in the past has been 29.67 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Sales Trends: The coin has been sold in 8 out of the 9 times it has been auctioned, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros, considering that the condition is not optimal and that the price history shows variations. A price of 80 euros could be a reasonable target, as it is a midpoint between the average hammer price and the maximum observed in previous auctions.

Therefore, the estimated maximum purchase price would be 80 euros.