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), indicating that it is in fairly good shape, but not of the highest quality (FDC).

2. Auction History:
- The average hammer price for similar coins in the past is 127.56 euros.
- The coin has been auctioned 20 times, of which it has sold 18 times, indicating good demand.
- Previous hammer prices for coins with a similar condition (75) have varied, but the most recent hammer price for a condition of 80 was 130 euros.

3. Starting Price and Estimates:
- The current starting price is 30 euros, which is quite low compared to the average hammer price.
- The average starting price for similar coins is 94.05 euros.

4. Price Trends:
- In previous auctions, hammer prices have shown a tendency to be significantly higher than starting prices, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price could be between 120 and 150 euros, considering that the condition is good and that the price history suggests buyers are willing to pay more than the starting price.

Therefore, a reasonable maximum purchase price could be 150 euros.