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

1. 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 auction prices: Previous hammer prices for coins with the same condition (95) have varied, but there is a range that can be observed:
- In recent auctions, hammer prices have been around 460 to 550 euros.
- The average hammer price for coins of similar condition is 506.76 euros.

3. Starting price: The current starting price is 350 euros, which is below the average hammer price observed in the past. This may indicate a good buying opportunity.

4. Auction trends: The coin has been auctioned 27 times, of which 22 have sold. This suggests that there is consistent interest in this coin, which can influence its value.

5. Price estimates: Estimated prices in previous auctions for coins in condition 95 have reached up to 750 euros, although this may be a more optimistic value.

Based on these factors, an estimated maximum purchase price could be in the range of 500 to 600 euros, considering that the average hammer price has been 506.76 euros and that the coin's condition is high.

Therefore, a reasonable maximum purchase price could be 550 euros.