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 that it is in relatively good shape, but not among the highest qualities.

2. Auction History:
- The average hammer price for similar coins has been 139.59 euros.
- In previous auctions, coins with similar conditions (75) have reached hammer prices of up to 200 euros (as seen in the auction on 2020-10-21).

3. Starting Price and Estimates:
- The current starting price is 110 euros, which is slightly higher than the average starting price of 102.84 euros.
- The estimated price for this auction is 125 euros, suggesting that bidders may be willing to pay more than the starting price.

4. Price Trends:
- In recent auctions, the hammer price has varied, but there have been examples where coins with similar conditions have reached hammer prices of 150 to 200 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is an important factor and that interest in the coin may be high.

Therefore, a reasonable maximum purchase price could be 180 euros. This allows for some margin for competition in the auction, given the history of hammer prices and the condition of the coin.