To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Starting Price: 90 euros. This is the initial price set for the auction.
2. Auction History: The coin has been auctioned 2 times in the past and has sold on both occasions. This indicates that there is interest in the coin.
3. Average Hammer Price: 92.5 euros. This is the average price at which it has sold in previous auctions, suggesting that buyers are willing to pay close to this value.
4. Condition: The coin has a condition rating of 10 (good), which is relatively low compared to other coins that may be in better condition. This may affect the maximum price that buyers are willing to pay.
5. Previous Prices: In the 2016 auction, the coin had a starting price of 40 euros and sold for 95 euros. This shows that, despite a low starting price, demand can drive the final price higher.

Given that the average hammer price is 92.5 euros and considering the condition of the coin, an estimated maximum purchase price could be slightly above the average hammer price, but not too high due to its condition.

Therefore, an estimated maximum purchase price could be around 100 euros. This reflects interest in the coin, but also takes into account its state of preservation.