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

1. Current 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. Previous Prices: Looking at previous auction prices for coins with a similar condition (95), we find that:
- In the auction on May 23, 2019, the hammer price was 340 euros.
- In the auction on April 25, 2018, the hammer price was 340 euros.
- In the auction on March 16, 2023, the hammer price was 500 euros.

3. Starting Price and Average Hammer Price: The current starting price is 300 euros, and the average hammer price for this coin is 205.58 euros. However, given the high condition, it is reasonable to expect that the hammer price will be above this average.

4. Market Trends: The coin has been auctioned 37 times, of which 33 have sold. This indicates a consistent interest in the coin, which may influence a higher hammer price.

5. Previous Estimates: The estimated price for the current auction is 350 euros, which can also serve as an indicator of what buyers are willing to pay.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 500 to 600 euros, as this is the range of hammer prices for coins of similar condition in recent auctions. However, given the interest and condition, a price of up to 600 euros could be reasonable if there is competition in the auction.