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 quite good shape. This is important because coins in better condition tend to fetch higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 175 euros. In previous auctions, we have seen hammer prices that vary, but there are examples of coins with similar conditions that have sold for prices ranging between 170 and 280 euros.

3. Price Trends: By observing the hammer prices from previous auctions, we can note that coins with a condition rating of 85 have reached hammer prices of up to 280 euros in the past. However, it is also important to consider that the market can fluctuate.

4. Average Hammer Price: The average hammer price for this coin is 150.12 euros, suggesting that the hammer price may be below the current starting price.

5. Analysis of Previous Sales: The coin has been auctioned 156 times, of which 151 have been successful sales. This indicates good demand in the market.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 250 euros, considering that the condition is good and there are precedents for higher hammer prices in the past. However, since the starting price is 175 euros, it is likely that the hammer price will not significantly exceed this value unless there is exceptional interest in the coin at the auction.

Therefore, a reasonable maximum purchase price could be 250 euros.