To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition of 75 (MBC), which indicates that it is in fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price for similar coins in the past has been 86.06 euros.
- In previous auctions, coins with similar conditions (around 75) have reached hammer prices that varied, but some examples are:
- 2021-06-22: Hammer price of 75 euros (condition 70).
- 2022-04-27: Hammer price of 90 euros (condition 80).
- 2023-05-23: Hammer price of 70 euros (condition 70).

3. Price Trends:
- The current starting price is 40 euros, which is below the historical average hammer price. This suggests that there may be interest in the coin, especially if the condition is good.

4. Comparison with Previous Prices:
- In previous auctions, coins with conditions from 70 to 80 have reached hammer prices between 70 and 90 euros. Given that the condition of this coin is 75, it is reasonable to expect that the hammer price will be in a similar range.

Based on these factors, an estimated maximum purchase price for this coin could be between 80 and 100 euros. This is based on the hammer price history for coins of similar condition and the potential interest in the coin.

Therefore, a reasonable maximum purchase price could be 90 euros.