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

1. Current Condition: The coin has a condition of 75 (MS), indicating that it is in quite good shape. This suggests that its value should be in a mid-high range.

2. Previous Prices: By looking at previous auction prices for coins with a similar condition (75), we can see that they have reached hammer prices of up to 50 euros in recent auctions. For example, at the auction on December 15, 2020, a coin with a condition of 75 was sold for 30 euros, and on other occasions, it has reached up to 50 euros.

3. Average Hammer Price: The average hammer price for this coin is 44.76 euros, which also indicates that the market value is in that range.

4. Auction Trends: The coin has been auctioned 46 times, of which 33 have resulted in sales. This suggests that there is a consistent interest in this coin, which may increase its value.

5. Starting Price: The starting price is 12 euros, which is relatively low compared to previous hammer prices.

Based on these factors, an estimated maximum purchase price for the coin could be between 50 and 70 euros, considering that the condition is good and that the interest in the coin seems to be solid. However, since the starting price is 12 euros, it is likely that the hammer price will not significantly exceed the observed average range.

Therefore, a reasonable estimated maximum purchase price could be 60 euros.