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

1. Current Condition: The coin has a condition of 75 (MBC), which indicates that it is in quite good shape. This suggests that its value should be above that of coins with lower conditions.

2. Auction History:
- The average hammer price from previous auctions is 81.43 euros.
- The last auction with a similar condition (75) had a hammer price of 75 euros.
- Overall, hammer prices have varied, but the range seems to be between 45 and 210 euros, depending on condition and other factors.

3. Starting Price and Estimates:
- The current starting price is 30 euros, which is relatively low compared to the average hammer price.
- The average starting price of similar coins is 41.43 euros, suggesting that the current starting price could be attractive to buyers.

4. Sales Trends: Since all coins of this reference have sold in the past, this indicates a steady demand.

Based on these factors, an estimated maximum purchase price could be in the range of 80 to 100 euros, considering that the condition is good and that the auction price history supports this estimate. Therefore, a reasonable maximum purchase price could be 90 euros.