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

1. Coin Condition: The coin has a condition of 70 (MS-), which indicates that it is in acceptable condition but not of high quality. This generally affects the price, as coins in better condition tend to fetch higher prices.

2. Auction History: By observing previous hammer prices of coins with a similar condition (70), we can see that the hammer price has varied. For example, in previous auctions, coins with a condition of 70 have reached hammer prices of 16, 15, 27, and 40 euros.

3. Average Hammer Price: The average hammer price for this coin is 92.21 euros, but this includes coins of different conditions. Given that the condition of this coin is 70, it is likely that the actual hammer price is below this average.

4. Starting Price and Previous Prices: The current starting price is 15 euros, and the average starting price in the past has been 63.1 euros. This suggests that the current starting price is relatively low compared to the historical average.

5. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 25 to 40 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 30 and 40 euros, considering that the condition is not the best and that the starting price is relatively low. Therefore, a reasonable maximum purchase price could be 35 euros.