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 quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for similar coins has been 136.73 euros.
- In previous auctions, the highest hammer price for coins with similar conditions (75) has been 35 euros (in 2022) and 30 euros (in 2021).
- However, there is a notably high hammer price of 380 euros in 2023 for a coin with a condition of 85, suggesting that there is potential for higher prices for good quality coins.

3. Starting Price and Average Starting Price: The current starting price is 30 euros, and the average starting price has been 60.57 euros. This suggests that the market is willing to pay more than the starting price on many occasions.

4. Sales Trends: The coin has been auctioned 17 times, of which 12 have sold. This indicates a consistent interest in the coin, which may influence the price.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 150 euros, considering that the condition is good and that the price history shows that buyers are willing to pay more for coins in good condition.

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