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 a medium-good quality. This is relevant because coins in better condition tend to fetch higher prices.

2. Starting Price and Average Hammer Price: The starting price is 75 euros, and the average hammer price in previous auctions is 100.37 euros. This suggests that, generally, coins of this reference tend to sell for above their starting price.

3. Sales History: The coin has been auctioned 126 times, of which it has sold 108 times. This indicates good demand and liquidity in the market.

4. Previous Prices: Looking at the hammer prices of coins with similar conditions (75-80), it can be seen that they have reached hammer prices that varied, but some have reached 130 euros or more in similar conditions.

5. Recent Trends: In the most recent auctions, hammer prices have shown an increase, which may indicate an upward trend in the value of this coin.

Based on these factors, an estimated maximum purchase price for this coin could be between 120 and 150 euros. This is based on the historical hammer prices and the current condition of the coin. However, it is important to note that the final price may vary depending on competition in the auction and other market factors at the time of sale.