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), 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 has been 72.48 euros.
- In previous auctions, coins with similar conditions (around 75) have reached hammer prices that varied, but some examples are:
- 2023-02-16: Hammer price of 85 euros (condition 80).
- 2022-07-07: Hammer price of 60 euros (condition 80).
- 2021-10-19: Hammer price of 33 euros (condition 80).

3. Price Trends:
- The current starting price is 18 euros, which is relatively low compared to the average hammer price.
- The average starting price in the past has been 41.99 euros, suggesting there is potential for an increase in the hammer price.

4. Comparison with Previous Prices:
- In previous auctions, the hammer price has varied considerably, but for similar conditions, prices have reached up to 100 euros in some cases.

Based on these factors, an estimated maximum purchase price for this coin could be between 80 and 100 euros, considering that the condition is good and that the price history suggests there is demand for coins in this condition range.

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