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

1. Current starting price: 250 euros.
2. Average starting price in previous auctions: 116.23 euros.
3. Average hammer price in previous auctions: 173.05 euros.
4. Auction history: The coin has been auctioned 24 times, of which it has sold 20 times, indicating a good sell-through rate.
5. Previous hammer prices: There are several hammer prices that exceed 200 euros, especially in high grades (100 and 95).

Since there is no information about the condition of the current coin, it is difficult to make an accurate estimate. However, considering that in previous auctions hammer prices have reached up to 360 euros and that the current starting price is 250 euros, we can infer that interest in this coin may be high.

### Maximum purchase price estimation:
- Based on the highest hammer price: 360 euros.
- Based on the current starting price: 250 euros.
- Considering the average hammer price: 173.05 euros.

Given that the starting price is 250 euros and considering the interest in the coin, a reasonable maximum purchase price could be in the range of 300 to 360 euros, depending on the competition in the auction and the condition of the coin.

Estimated maximum purchase price: 350 euros.