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

1. Current Condition: The coin has a condition of 75 (MBC), which is a fairly good state. This suggests that its value could be in the mid-high range of previous auctions.

2. Previous Prices: Looking at previous auction prices for coins with a similar condition (75), we see that they have ranged between 9 and 25 euros. The average hammer price for coins with a condition of 75 has been approximately 12 to 20 euros.

3. Average Hammer Price: The average hammer price for this particular coin has been 19.25 euros, indicating that in the past it has reached prices close to this value.

4. Recent Trends: In the most recent auctions, hammer prices have shown a range of 12 to 30 euros for similar conditions, suggesting that there is growing interest in this coin.

5. Starting Price: The starting price is 9 euros, which is relatively low compared to previous hammer prices.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 25 euros. This is based on recent interest and previous hammer prices for coins of similar condition.