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 the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 63.37 euros.
- It has been auctioned 29 times, of which 13 have sold, indicating a sell-through rate of 44.83%. This suggests there is interest in the coin, but it does not always sell.

3. Previous Prices:
- In past auctions, hammer prices have varied. For example, in 2016 it sold for 120 euros in a condition of 90, and on other occasions, it has ranged between 60 and 80 euros in conditions similar to the current one.

4. Starting Price: The starting price is 50 euros, which is a good starting point, but the hammer price is usually higher.

5. Recent Trends: In recent auctions, hammer prices have been in the range of 70 to 80 euros for similar conditions.

Based on these factors, an estimated maximum purchase price could be between 70 and 80 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. Therefore, a reasonable maximum purchase price could be 80 euros.