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

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. Starting Price and Average Hammer Price: The starting price is 90 euros, and the average hammer price in previous auctions is 148.89 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Sales History: The coin has been auctioned 42 times, of which 38 have resulted in sales. This indicates good demand and consistent interest in this coin.

4. Previous Prices: By looking at previous hammer prices for coins with similar conditions (85 and 90), we can see that they have reached hammer prices that vary, but some have exceeded 150 euros.

5. Recent Trends: In the most recent auctions, hammer prices have shown an increase, which could indicate an upward trend in the value of this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros. This is based on the average hammer price and the condition of the coin, as well as the price trend in previous auctions.

Therefore, a reasonable maximum purchase price could be 180 euros.