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

1. Current Condition: The coin has a condition of 30 (BC+). This indicates that it is not in the best condition, which generally negatively affects its value.

2. Historical Prices: By looking at previous auction prices for coins with similar conditions, we can see that prices vary considerably. For example, in past auctions, coins with conditions ranging from 25 to 30 have had hammer prices ranging from 9 to 40 euros.

3. Average Hammer Price: The average hammer price for this coin is 114.55 euros, but this includes coins in better conditions. Given that the condition of this coin is lower, it is unlikely to reach that price.

4. Starting Price and Average Starting Price: The starting price is 12 euros, and the average starting price is 59.77 euros. This suggests that the market has moderate expectations for this coin.

5. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been lower, suggesting that interest may be declining.

Based on these factors, an estimated maximum purchase price for this coin could be between 25 and 35 euros. This reflects a balance between the current condition and historical prices, taking into account that market interest may influence the final price.