To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Condition: The coin has a condition rating of 95 (S/C-), indicating that it is in very good shape. This generally increases its value compared to coins with lower conditions.

2. Previous auction prices:
- In December 2020, the coin was auctioned with a starting price of 1700 euros and sold for 2200 euros, indicating significant interest in that condition.
- In December 2021, although the final price was lower (950 euros), the condition was 85, suggesting that condition drastically affects the price.
- In March 2024, the starting price is 2500 euros with an estimated price of 4000 euros, indicating that the market continues to value this coin well in good condition.

3. Average starting and final prices: The average starting price is 1900 euros and the average final price is 1575 euros. This suggests that, in general, coins of this reference tend to sell below their starting price, but interest may vary depending on the condition.

4. Market trends: Since the coin has been auctioned several times and has had a high final price in the past, this suggests that there is an active market for this coin, especially in good condition.

Based on these factors, an estimated maximum purchase price could be between 2200 and 2500 euros, considering that the condition is high and there has been interest in the past. However, since the current starting price is 1500 euros, it could be a good buying opportunity if it can be acquired below that range.

Therefore, a reasonable maximum purchase price could be 2400 euros.