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

1. Condition: The coin has a condition rating of 95 (S/C-), which is quite high. This generally indicates that the coin is in very good shape, which can increase its value.

2. Auction History:
- The average hammer price for this coin in the past is 555.75 euros.
- In previous auctions, hammer prices have varied, but there are several examples where the coin has sold for over 600 euros, especially in similar conditions.

3. Starting Price: The current starting price is 450 euros, which is reasonable given the price history.

4. Recent Trends: In the most recent auctions, hammer prices have been in the range of 600 to 900 euros, suggesting that there is growing demand for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 650 to 750 euros. This is based on the hammer price history and the high condition of the coin. However, since the market can be volatile, it is important to consider the competition in the auction and the willingness of other bidders to pay.