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

1. Coin Condition: The coin has a condition rating of 95 (EBC+), 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: By looking at the hammer prices of coins with a similar condition (95), we can see that they have reached hammer prices of up to 1400 euros in the past (as seen in the auction on 2020-01-23). However, most hammer prices for coins in condition 95 seem to be in a lower range, around 400-750 euros.

3. Starting Price and Average Hammer Price: The current starting price is 450 euros, and the average hammer price for similar coins is 313.25 euros. This suggests that the starting price is reasonable, but it also indicates that there could be competition in the auction that might drive the price up.

4. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have been in the range of 360-400 euros, suggesting that interest in high-condition coins remains strong.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 600 to 800 euros. This range takes into account the high condition of the coin and previous hammer prices, as well as the possibility that competition in the auction could raise the price.