To estimate a maximum purchase price for the coin in question, we will 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. Historical Prices: By looking at previous auction prices for coins with similar conditions (around 85), we can see that the hammer prices have varied. For example:
- In previous auctions, coins with a condition of 85 have reached hammer prices between 90 and 130 euros.
- The average hammer price for coins in similar condition seems to be around 100-120 euros.

3. Starting Price and Average Hammer Price: The current starting price is 75 euros, and the average hammer price in the past has been 140.09 euros. This suggests that there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, hammer prices for coins in similar condition have shown an increase, which could indicate a rising trend in interest for these coins.

Based on these factors, an estimated maximum purchase price for this coin could be between 120 and 150 euros. This is based on the current condition, previous hammer prices, and market trends.

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