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

1. Coin Condition: The coin has a condition rating of 85 (ebc-), which indicates 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 52.95 euros.
- In previous auctions, coins with a similar condition (85) have reached hammer prices that vary, but some examples are:
- 50 euros (2020-12-15)
- 55 euros (2020-05-26)
- 95 euros (2020-09-17, although with a condition of 95)
- 70 euros (2018-10-16, condition 85)
- 90 euros (2022-10-18, condition 85)

3. Starting Price: The starting price is 50 euros, indicating that this is the minimum expected to be obtained at the auction.

4. Price Trends: Looking at the history, it seems that coins with a condition of 85 have had a hammer price range from 50 to 90 euros, depending on demand and other market factors.

Based on these points, an estimated maximum purchase price for this coin could be around 70-80 euros, considering that the condition is good and there is interest in the coin. This also allows for a margin for competition in the auction.