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 generally translates to a higher price compared to coins with lower conditions.

2. Current Starting Price and Previous Prices: The current starting price is 90 euros, and the average hammer price in previous auctions is 148.42 euros. This suggests that the coin has a selling potential above the starting price.

3. Sales History: In the past, the coin has had hammer prices that varied significantly, ranging from 55 euros to 550 euros, depending on the condition and demand at the time of the auction. However, the highest hammer prices have been for coins in better condition (95).

4. Recent Trends: In the most recent auctions, hammer prices have been quite high, such as the 460 euros in January 2023 for a coin with a condition of 90.

5. Condition-Based Estimation: Given that the coin's condition is 85, we can estimate that its hammer price could be in a higher range than average, but not as high as those with a condition of 95.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 200 and 300 euros, considering that the average hammer price is 148.42 euros and that the condition is relatively good.

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