To estimate a maximum purchase price for the coin in question, we can analyze several factors:

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in fairly good shape, although not the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 30.44 euros.
- In past auctions, the coin has reached hammer prices of up to 40 euros in its best condition (80) and 32 euros in a similar condition (75).
- The price trend appears to be increasing, with recent auctions achieving higher prices.

3. Starting Price: The starting price is 20 euros, which is relatively low compared to previous hammer prices.

4. Comparison with Previous Prices:
- In the most recent auction (2023-01-31), the coin sold for 40 euros with a condition of 80.
- In the auction on 2022-10-17, with a condition of 75, it sold for 25 euros.

Based on this data, an estimated maximum purchase price could be between 35 and 45 euros, considering that the current condition is good and interest in the coin seems to be increasing. A price of 40 euros could be a reasonable target, as it is a midpoint between previous hammer prices and the current condition.