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

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

2. Auction History: By observing previous hammer prices, we can see that there is significant variability. However, the highest hammer prices have been for coins with conditions of 95, which have reached prices of up to 1700 euros.

3. Average Hammer Price: The average hammer price for this coin is 212.67 euros, which can serve as a good reference point.

4. Price Trends: The coin has had a starting price of 15 euros, but the average starting price in previous auctions is 100.38 euros. This suggests that the market is willing to pay more than the starting price.

5. Comparison with Similar Coins: In previous auctions, coins with similar conditions (70-80) have reached hammer prices that vary, but are generally in the range of 30 to 220 euros.

Taking all these factors into account, an estimated maximum purchase price for the coin with a condition of 75 could be in the range of 200 to 300 euros, considering that the average hammer price is 212.67 euros and that the condition is relatively good.

Therefore, an estimated maximum purchase price could be 250 euros.