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

1. Current Condition: The coin has a condition of 85 (ebc-), indicating that it is in quite good shape. This suggests that its value should be in the upper range of previous auctions.

2. Previous Prices: Looking at previous auction prices for coins with similar conditions:
- A coin with a condition of 85 sold for 45 euros in a previous auction.
- Another coin with a condition of 85 sold for 70 euros.
- There is also a sale of 55 euros for a coin with a condition of 85.

3. Average Hammer Price: The average hammer price for previously auctioned coins is 39.86 euros, providing additional context.

4. Starting Price and Estimates: The current starting price is 15 euros, and the average starting price is 26.92 euros. This suggests that the market is willing to pay more than the starting price.

5. Auction Trends: Since the coin has been auctioned 10 times and sold 7 of those times, there is good demand for this reference.

Based on these factors, an estimated maximum purchase price could be in the range of 70 to 90 euros, considering that the condition is good and there are precedents for sales in that range. However, to be more conservative and taking into account the starting price, a reasonable maximum purchase price could be 75 euros.