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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for coins of this reference is 76.63 euros.
- In previous auctions, hammer prices have varied, but there are examples of sales reaching up to 95 euros (as in the 2024 auction).

3. Price Trends:
- The coin has been auctioned 9 times, of which 8 have sold. This indicates good demand.
- The current starting price is 30 euros, which is reasonable compared to the average hammer price.

4. Comparison with Previous Prices:
- In previous auctions, the hammer price has been 80 euros (2020) and 85 euros (2019 and 2023), suggesting that the hammer price may be in a similar or higher range.

Based on these factors, an estimated maximum purchase price could be in the range of 80 to 95 euros, considering that the coin's condition is good and there has been interest in previous auctions.

Therefore, a reasonable estimated maximum purchase price could be 90 euros.