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 relatively good shape, but not among the best qualities. This can influence the price, as coins in better condition tend to fetch higher prices.

2. Auction History:
- The average hammer price for similar coins in the past is 1301.11 euros.
- The last auction where a coin with a similar condition (70) was sold had a hammer price of 910 euros, while one with a condition of 80 sold for 1200 euros.
- The highest recorded auction was 2100 euros for a coin with a condition of 95.

3. Starting Price and Estimates:
- The current starting price is 1400 euros, which is above the average starting price of 1069.44 euros.
- The estimated price of 2500 euros in a previous auction was not reached, suggesting that there may be expectations for higher prices, but also that the market does not always respond to these expectations.

4. Sales Trends: The coin has sold in 9 out of the last 10 auctions, indicating a consistent interest in the coin.

Based on these factors, an estimated maximum purchase price could be between 1300 and 1600 euros, considering that condition is an important factor and that the average hammer price is 1301.11 euros. Given that the starting price is 1400 euros, a reasonable maximum purchase price could be approximately 1500 euros. This allows for a margin to compete in the auction without exceeding the starting price too much.