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 an acceptable state, but not among the best qualities.

2. Historical Prices: By looking at previous auction prices for coins with similar conditions (around 75-80), we can see that the hammer prices have varied. For example:
- In previous auctions, coins with a condition of 75 have reached hammer prices of up to 220 euros.
- The average hammer price for coins of similar condition seems to be around 100-170 euros.

3. Starting Price and Average Hammer Price: The current starting price is 125 euros, and the average hammer price in the past has been 104.53 euros. This suggests that the starting price is reasonable, but it does not necessarily indicate that a high hammer price will be reached.

4. Sales Trends: The coin has been auctioned 72 times, of which 60 have been successful sales. This indicates good demand, which may influence the price.

5. Comparison with Previous Prices: In previous auctions, the highest hammer price for a coin of similar condition was 400 euros, but that was in a different context and with slightly better condition.

Based on these factors, an estimated maximum purchase price for this coin could be between 150 and 200 euros. This is based on the current condition, previous hammer prices, and sales trends. A price of 200 euros could be a reasonable upper limit, considering that the starting price is 125 euros and there is interest in the coin.