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

1. Coin Condition: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 242.21 euros.
- There have been previous auctions where the coin has sold for significantly higher prices, such as 700 euros in 2017 and 900 euros in 2023, indicating a potential for high demand.

3. Current Starting Price: The starting price is 300 euros, suggesting that the seller has expectations of a higher hammer price.

4. Recent Trends: In the most recent auctions, hammer prices have shown an upward trend, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price could be in the range of 600 to 800 euros, considering that the condition is high and there are precedents for sales at higher prices. However, since the starting price is 300 euros, it is likely that the hammer price will not significantly exceed this range unless there is active competition among bidders.

Therefore, a reasonable maximum purchase price could be 750 euros.