To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Coin Condition: The coin has a condition of 85 (MBC+/EBC-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By looking at the hammer prices of coins with a similar condition (85), we can see that they have reached hammer prices that vary but are generally in a high range. For example:
- In previous auctions, coins with a condition of 85 have reached hammer prices of 160 euros (2020-12-16) and 140 euros (2020-05-26).

3. Average Hammer Price: The average hammer price for this coin is 128.61 euros, which is also an important indicator.

4. Starting Price and Average Starting Price: The current starting price is 75 euros, and the average starting price is 84.88 euros. This suggests that the starting price is reasonable compared to the market value.

5. Market Trends: Since the coin has been auctioned 209 times and sold 186 times, there is good demand and liquidity in the market for this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and there are precedents for hammer prices in that range.

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