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+), which is relatively low compared to other coins that have been auctioned in the past. This may negatively affect its value.

2. Previous Auction Prices: By looking at previous hammer prices for coins with similar conditions, we can see that:
- In past auctions with a condition of 30, the hammer prices have been 12 and 50 euros.
- Most coins with higher conditions (70 and 80) have reached hammer prices ranging from 60 to 150 euros.

3. Starting Price and Average Hammer Price: The current starting price is 60 euros, and the average hammer price for similar coins is 75.22 euros. This suggests that the market is willing to pay a little more than the starting price.

4. Auction Trends: The coin has been auctioned 23 times in the past, of which it has sold 10 times. This indicates a moderate interest in the coin, but also that there is a significant number of auctions where it has not sold.

5. Price Estimates: Based on the starting price and the average hammer price, as well as previous hammer prices for similar conditions, an estimated maximum purchase price could be between 50 and 70 euros, considering that the current condition is low.

Conclusion: An estimated maximum purchase price for this coin could be approximately 70 euros, taking into account the condition and previous hammer prices.