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

1. Current Condition: The coin has a condition rating 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 similar coins has been 65.64 euros.
- In previous auctions, hammer prices have varied, but there are examples of sales reaching up to 95 euros (as seen in the auction on September 19, 2024).

3. Starting Price and Average Starting Price: The current starting price is 30 euros, and the average starting price in the past has been 43.6 euros. This suggests that the current starting price is relatively low compared to the historical average.

4. Sales Trends: Out of the 15 times it has been auctioned, it has sold on 13 occasions, indicating good demand for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros, considering that the condition is good and there are precedents for sales in that range. However, since the average hammer price is 65.64 euros, a more conservative maximum purchase price could be around 80 euros.

Therefore, a reasonable estimated maximum purchase price would be 80 euros.