To estimate a maximum purchase price for the coin in question, we can 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 can influence the price, as coins in better condition tend to reach higher prices.

2. Auction History: By observing the hammer prices of coins with a similar condition (70) in the past, we can see that they have reached varying hammer prices. For example, in previous auctions, coins with a condition of 70 have had hammer prices ranging from 15 to 25 euros.

3. Average Hammer Price: The average hammer price for this coin is 67.1 euros, but this may be influenced by coins in better condition. Given that the condition of this coin is lower, it is likely that the actual hammer price will be lower.

4. Starting Price and Previous Prices: The current starting price is 12 euros, and the average starting price in the past has been 48.1 euros. This suggests that there is potential for an increase in the hammer price, but also that interest may vary.

5. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have been in the range of 20 to 30 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 25 and 35 euros, considering that the condition is not the best and that collector interest may influence the final price.