To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the condition of the coin.

1. Starting price: 150 euros.
2. Average hammer price: 91.9 euros.
3. Previous hammer prices:
- Previous hammer prices varied significantly, with some reaching up to 280 euros in favorable conditions.
- Most hammer prices are in the range of 35 to 150 euros, with some exceptional cases.

4. Condition: No information is provided about the condition of this coin, which makes the estimation more complicated. However, we can observe that in previous auctions, coins with higher conditions (95) have reached hammer prices of up to 160 euros.

5. Trends: The coin has been auctioned 40 times, of which 31 have sold. This indicates a consistent interest in the coin, which may influence its price.

Given that there is no information about the condition of this coin and considering the previous hammer prices, an estimated maximum purchase price could be in the range of 150 to 200 euros, depending on the demand at the auction and collectors' perception of its value.

Maximum purchase estimate: 200 euros.