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

1. Current Condition: The coin has a condition of 75 (MBC), which indicates that it is in fairly good shape, but not among the best qualities (FDC).

2. Historical Prices: By looking at the auction prices of coins with similar conditions (around 75-90), we can see that the auction prices have varied. For example:
- In previous auctions, coins with a condition of 85 have reached auction prices of up to 220 euros.
- Coins with a condition of 90 have reached auction prices of up to 300 euros.

3. Average Auction Price: The average auction price for this particular coin is 95.48 euros, which gives us a good reference.

4. Starting Price and Estimates: The current starting price is 15 euros, and the average starting price in the past has been 72.14 euros. This suggests that interest in the coin may be greater than the starting price.

5. Recent Trends: In the most recent auctions, the auction prices have shown a range that may indicate an increase in interest for coins of this condition.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 120 to 180 euros, considering that the condition is good and there is a price history that supports this estimate.

Therefore, a reasonable maximum purchase price could be 150 euros.