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), which indicates that it is in an acceptable state, but not among the best qualities. This may influence the price, as coins in better condition tend to reach higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 1400 euros. In previous auctions, the average hammer price has been 1268.91 euros, suggesting that the current starting price is slightly higher than the average of what has been sold in the past.

3. Price Trends: Looking at previous hammer prices, there are examples of similar coins that have reached hammer prices of up to 2200 euros in higher condition ratings (such as 90 and 95). However, the condition of this coin is lower, suggesting it will not reach those maximum prices.

4. Supply and Demand: The coin has been auctioned 24 times in the past, with a sell-through rate of 95.83% (23 out of 24). This indicates a consistent interest in this coin, which may help maintain its price.

5. Estimation Based on Historical Data: Given that the average hammer price has been 1268.91 euros and considering the condition of 75, a reasonable hammer price could be in the range of 1200 to 1600 euros, depending on the competition in the auction.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 1600 euros. This price reflects a balance between the current condition, historical prices, and market demand.