To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the current grade of the coin (85, ebc-) and the hammer prices from previous auctions.

1. Grade: The coin has a grade of 85, indicating that it is in fairly good condition, but not the best possible condition. This suggests that its price should be below that of coins in better condition.

2. Previous hammer prices: Looking at the hammer prices from previous auctions for coins with similar grades:
- In 2020, a coin with a grade of 75 sold for 100 euros.
- In 2020, another coin with a grade of 90 sold for 150 euros.
- In 2021, a coin with a grade of 70 sold for 160 euros.
- In 2022, a coin with a grade of 80 did not have a hammer price, but it was estimated at 225 euros.

3. Price trends: The average hammer price for previously auctioned coins is 121.82 euros, which can serve as a reference.

4. Starting price: The current starting price is 175 euros, indicating that the seller has high expectations, but this does not always translate into a high hammer price.

Based on these factors, an estimated maximum purchase price could be in the range of 120 to 160 euros, considering that the coin's condition is good but not excellent, and that previous hammer prices for similar grades have varied.

Therefore, a reasonable estimated maximum purchase price could be 150 euros.