To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 75 (MBC), indicating that it is in quite good shape.

2. Previous Auction Prices:
- In previous auctions, we have seen varying hammer prices, but there are some relevant data points:
- In 2022, a coin with a condition of 75 was auctioned for 75 euros.
- In 2021, a coin with a condition of 95 was auctioned for 420 euros, indicating that condition has a significant impact on price.
- In 2022, another coin with a condition of 85 was auctioned for 90 euros.

3. Price Trends:
- The average hammer price for this coin is 119.1 euros, suggesting that, in general, buyers are willing to pay more than the starting price.

4. Starting Price and Estimates:
- The current starting price is 30 euros, and the average starting price in the past has been 40 euros. However, the average hammer price is significantly higher.

Given that the condition of the coin is 75 and considering the previous auction prices, an estimated maximum purchase price could be in the range of 75 to 120 euros.

Therefore, a reasonable estimated maximum purchase price could be 100 euros. This is based on the trend of previous hammer prices and the current condition of the coin.