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

1. Current Condition: The coin has a grade of 70 (MS-). This indicates that it is in an acceptable state, but it is not of the highest quality.

2. Previous Auction Prices: By observing the auction prices of coins with a similar grade (70), we can see that the hammer price has varied. For example, in previous auctions, coins with a grade of 70 have reached hammer prices of up to 110 euros.

3. Average Hammer Price: The average hammer price for this coin is 101.29 euros, which gives us a good reference for what buyers are willing to pay.

4. Recent Trends: In the most recent auctions, the hammer price has shown a trend of increasing, especially for coins in good condition. This suggests that there may be growing interest in this coin.

5. Starting Price: The starting price is 50 euros, which is relatively low compared to previous hammer prices.

Based on these factors, an estimated maximum purchase price for this coin could be between 110 and 130 euros, considering that interest in the coin may lead to competitive bidding. However, since the condition is not the highest, it is wise not to exceed 130 euros in the bidding.