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

1. Current Condition: The coin has a condition of 85 (ebc-), which indicates that it is in fairly good shape, but not the best possible condition.

2. Previous Auction Prices: By looking at the hammer prices from previous auctions for coins with similar conditions, we can see that:
- In 2014, a coin with a condition of 85 sold for 48.14 euros.
- In 2022, a coin with a condition of 85 sold for 70 euros.
- In 2021, a coin with a condition of 90 sold for 90 euros.

3. Average Hammer Price: The average hammer price for this coin is 77.22 euros, which gives us a good reference for what buyers are willing to pay.

4. Starting Price: The starting price is 55 euros, which is a good starting point, but generally, the hammer price tends to be higher.

5. Market Trends: Given that the coin has been auctioned 38 times and has a sales history, this indicates a consistent interest in it.

Based on these factors, an estimated maximum purchase price could be between 80 and 90 euros, considering that the condition is good and the average hammer price is around 77.22 euros. This also takes into account the increase in hammer prices in recent auctions.

Therefore, a reasonable maximum purchase price could be 90 euros.