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

1. Coin Condition: The coin to be auctioned has a condition of 95 (S/C-), indicating that it is in very good shape. This is a positive factor that can increase its value.

2. Starting Price: The starting price is 450 euros. This is the starting point for the auction.

3. Price History: By looking at the hammer prices from previous auctions for coins with a similar condition (95), we can see that in the past, hammer prices have varied. For example:
- In 2018, a coin with a condition of 95 was auctioned with a starting price of 600 euros and sold for 600 euros.
- In 2014, another coin with a condition of 95 was auctioned with a starting price of 250 euros and sold for 850 euros.

4. Price Trends: The average hammer price for similar coins is 205.85 euros, but this may be influenced by coins of lower condition. Given that the condition of this coin is high, it is reasonable to expect that the hammer price will be significantly higher.

5. Sales Expectations: Since there have been 50 previous auctions and 47 of them have sold, this indicates high demand and sustained interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 600 and 900 euros, considering that the condition is high and that in the past, hammer prices in that range have been reached for similar coins.

Therefore, a reasonable maximum purchase price could be 800 euros.