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: Looking at previous auction prices for coins with a similar condition (95), we find:
- In 2019, a coin with a condition of 95 was auctioned for 280 euros.
- In 2020, another coin with the same condition was auctioned for 155 euros.

3. Current Starting Price: The starting price is 450 euros, which is significantly higher than previous auction prices. This may indicate that the seller expects considerable interest in the coin.

4. Sales Trends: The coin has been auctioned 36 times, of which 31 have resulted in sales. This suggests that there is an active market for this coin.

5. Average Auction Price: The average auction price for similar coins is 120.1 euros, but this may be influenced by coins of lower condition.

Given that the condition of the coin is high and considering previous auction prices, an estimated maximum purchase price could be in the range of 250 to 300 euros, assuming that interest in the coin remains and that buyers are willing to pay a higher price for a coin in excellent condition.

Therefore, an estimated maximum purchase price could be 300 euros.