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 of 75 (MBC), which is a fairly good state. This suggests that its value should be in a higher range than coins in worse conditions.

2. Previous Auction Prices: By looking at previous auction prices for coins with a similar condition (75), we can see that they have reached auction prices of up to 65 euros in recent auctions.

3. Average Auction Price: The average auction price for this coin is 52.02 euros, which also indicates a reasonable value range.

4. Auction Trends: The coin has been auctioned 80 times, of which 69 have resulted in sales. This indicates good demand and sustained interest in the coin.

5. Starting Prices and Estimates: The current starting price is 25 euros, and the average starting price is 31.39 euros. This suggests that the starting price is below market value, which could attract more bidders.

6. Comparison with Previous Prices: In previous auctions, coins with a condition of 75 have had auction prices that varied, but the highest has been 65 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 60 to 70 euros. This is based on the condition, previous auction prices, and the trend of demand in the market.