To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating a medium-low quality. This may influence the price, as coins in better condition tend to fetch higher prices.

2. Starting Price and Average Hammer Price: The starting price is 175 euros, and the average hammer price in previous auctions is 406.91 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Sales History: The coin has been auctioned 87 times, of which 79 have been sold. This indicates good demand and consistent interest in this coin.

4. Previous Prices: Looking at the hammer prices of coins with a similar condition (75), we can see that they have reached hammer prices that vary, but some have reached 360 euros in recent auctions.

5. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 270 to 425 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 350 to 400 euros. This is based on the hammer price history and the current condition of the coin. However, given that interest in the coin appears to be high, a price of up to 425 euros could be reasonable if there is competition in the auction.