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 75 (MBC), indicating that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 114.64 euros.
- The coin has been auctioned 19 times, of which it has sold 15 times, indicating good demand.
- Previous hammer prices for similar conditions (70-85) have varied, with some reaching significantly higher prices (for example, 600 euros in 2018 for a condition of 85).

3. Starting Price: The starting price is 100 euros, which can be a good indicator of the expected minimum value.

4. Price Trends: Observing previous hammer prices, there is a trend for coins in good condition (like the one rated 75) to sell above the starting price, especially if there is interest in the auction.

Given all this, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and there is a history of hammer prices suggesting it could reach higher figures in competitive auctions.

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