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

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 in lower conditions.

2. Auction History:
- The average hammer price in previous auctions is 83.27 euros.
- The coin has been auctioned 40 times, of which it has sold 34 times, indicating good demand.
- In recent auctions, the hammer price has varied, but there are examples of sales exceeding 100 euros, especially for coins in similar or better conditions.

3. Starting Price and Average Starting Price:
- The current starting price is 50 euros, and the average starting price in the past has been 53.97 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Recent Trends: In the most recent auctions, hammer prices have been higher, which could indicate an upward trend in the value of this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 90 to 110 euros. This is based on the average hammer price and the condition of the coin, as well as the price trends in recent auctions.

Therefore, a reasonable maximum purchase price could be 100 euros.