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

1. Current Condition: The coin has a condition rating of 85 (EF-), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins has been 109 euros.
- In previous auctions, coins with a similar condition (85) have reached hammer prices of up to 140 euros (as seen in the auction on 2019-10-17).
- The last auction with a condition of 85 had a hammer price of 75 euros (2022-10-17).

3. Starting Price and Average Starting Price: The current starting price is 60 euros, and the average starting price in the past has been 64.05 euros. This suggests that the starting price is reasonable and aligns with historical expectations.

4. Sales Trends: The coin has been sold in 35 out of 40 auctions, indicating good demand. This may influence a higher hammer price.

5. Previous Estimates: In past auctions, the estimated price for coins with similar conditions has varied, but it has reached up to 150 euros in some cases.

Based on these factors, an estimated maximum purchase price for this coin could be between 100 and 140 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 120 euros.