To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Condition: The coin has a condition of 85 (ebc-), which is a fairly good state. This suggests that its value should be in the upper range of previous auctions.

2. Previous Prices:
- The average hammer price for coins with the same condition (85) has been 91.25 euros.
- In previous auctions, hammer prices have varied, but they have been in a range of 75 to 120 euros.

3. Starting Price: The current starting price is 70 euros, which is reasonable given the history of starting and hammer prices.

4. Trends: The coin has sold in 4 out of the last 5 auctions, indicating a consistent interest in this reference. Additionally, the average hammer price (91.25 euros) suggests that buyers are willing to pay more than the starting price.

5. Estimation: Given that the average hammer price is 91.25 euros and considering that the coin has a condition of 85, an estimated maximum purchase price could be in the range of 90 to 110 euros, depending on the competition in the auction.

Conclusion: An estimated maximum purchase price for this coin could be approximately 100 euros. This is based on the price history and the condition of the coin.