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 70 (MS-), indicating that it is in relatively good shape. This suggests that its value should be in the upper range of coins with a similar condition.

2. Previous Auction Prices: Looking at previous auction prices for coins with a similar condition (70), we can see that they have reached auction prices of up to 110 euros in past auctions. However, there are also lower prices, such as 41 euros.

3. Average Auction Price: The average auction price for this coin is 86.77 euros, which provides a good reference point.

4. Recent Trends: In the most recent auctions, auction prices for coins with a condition of 70 have been in the range of 75 to 120 euros.

5. Starting Price: The starting price is 50 euros, which is reasonable and could attract more bidders.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 120 euros, considering that the condition is good and there is a history of auction prices that supports this estimate.

Therefore, an estimated maximum purchase price for this coin could be 110 euros.