To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current Condition: The coin has a condition 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. Auction History:
- The average hammer price for this coin in the past is 140.69 euros.
- In previous auctions, the hammer price has varied, but there are examples of sales exceeding 140 euros, especially in similar conditions (for example, in the 2020 auction where it sold for 140 euros with a condition of 85).

3. Starting Price: The starting price is 75 euros, which is a good starting point for the auction.

4. Price Trends: Observing previous hammer prices, it seems there is a trend for coins in similar conditions to sell for above 100 euros, and in some cases, much more.

Given that the condition of the coin is 85 and considering the hammer price history, an estimated maximum purchase price could be in the range of 140 to 160 euros. This is based on the average hammer price and the fact that condition is a key factor that can increase collector interest.

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