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 grade of 70 (MS-), indicating that it is in relatively good condition. This suggests that its value should be above that of coins in worse conditions.

2. Previous Auction Prices: By looking at previous auction prices for coins with a similar grade (70), we can see that they have reached auction prices of up to 130 euros in recent sales. For example, at the auction on April 28, 2022, a coin with a grade of 70 sold for 130 euros.

3. Average Auction Price: The average auction price for this coin is 91.06 euros, which can also serve as a reference.

4. Auction Trends: The coin has been auctioned 59 times, of which 55 have been sold. This indicates good demand and sustained interest in the coin.

5. Starting Price: The starting price is 50 euros, which is a good starting point, but given the auction price history, it is likely that the final price will be significantly higher.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 120 and 150 euros, considering that the condition is good and there is a price history that supports this estimate.