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 (ebc-), which indicates that it is in quite good shape. In the past, coins with a similar condition have reached auction prices that vary, but are generally in a high range.

2. Previous Auction Prices: By observing the hammer prices of coins with a condition of 85, we can see that they have reached hammer prices of up to 140 euros in previous auctions. For example, in 2018, a coin with a condition of 85 was auctioned for 120 euros and another for 110 euros.

3. Average Hammer Price: The average hammer price for this coin is 65.27 euros, but given that the condition is good, we can expect the hammer price to be above this average.

4. Starting Price: The starting price is 75 euros, which indicates that the seller expects a reasonable minimum price.

5. Auction Trends: Since it has been auctioned 117 times and sold 105 times, demand seems to be high, which could increase the hammer price.

Based on these factors, an estimated maximum purchase price could be between 120 and 150 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 150 euros.