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 (EBE-), 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 140 euros, and the average hammer price in previous auctions is 136.65 euros. This suggests that the hammer price tends to be close to the starting price.

3. Sales History: The coin has been auctioned 242 times, of which it has sold 221 times. This indicates good demand and liquidity in the market.

4. Previous Prices: Looking at previous hammer prices for coins with similar conditions (around 80-85), it can be seen that they have reached hammer prices that varied considerably, but some have reached up to 700 euros in exceptional conditions.

5. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have been in the range of 150 to 360 euros, depending on demand and supply at the time of the auction.

Based on these factors, an estimated maximum purchase price for this coin could be between 200 and 300 euros, considering that the condition is good and there is a trend of rising prices in the market. However, given the starting price of 140 euros, it is likely that the hammer price will not significantly exceed this range unless there is intense competition in the auction.

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