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: By looking at previous auction prices for coins with a similar condition (95), we can see that they have reached hammer prices of up to 500 euros in recent auctions. For example, in the 2020 auction, the coin sold for 500 euros with a condition of 100, and in other auctions with a condition of 95, the hammer prices have been around 395 to 500 euros.

3. Starting Price and Average Hammer Price: The current starting price is 350 euros, and the average hammer price in the past has been 365.96 euros. This suggests that the hammer price could be in a similar range or slightly higher.

4. Auction Trends: The coin has been auctioned 29 times, with a sell-through rate of 93% (27 out of 29). This indicates consistent demand, which may influence a higher hammer price.

5. Maximum Price Estimate: Given that the highest hammer price in the past has been 500 euros and considering the current condition, a reasonable maximum purchase price could be in the range of 450 to 550 euros. This is based on previous price trends and the good condition of the coin.

Therefore, an estimated maximum purchase price for this coin could be approximately 500 euros.