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 (ebc-), indicating that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for similar coins has been 42.55 euros.
- In previous auctions, coins with a similar condition (85) have had hammer prices that vary, but some examples are:
- 40 euros (2020-11-10)
- 30 euros (2020-11-03)
- 36 euros (2017-07-05)
- 50 euros (2017-09-21)
- The trend shows that the hammer price can be in a range of 30 to 50 euros for similar conditions.

3. Starting Price and Average Starting Price:
- The starting price is 15 euros, and the average starting price is 30.64 euros. This suggests that the hammer price could be significantly higher than the starting price.

4. Recent Trends:
- Recent auctions have shown increasing interest, with hammer prices sometimes exceeding 50 euros for coins in similar conditions.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 45 to 60 euros. This is based on the historical hammer prices for coins of similar condition and the trend of prices in recent auctions.