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 with lower conditions.

2. Auction History:
- The average hammer price for similar coins has been 80.88 euros.
- In the past, coins with a similar condition (around 75) have had hammer prices that varied, but some examples are:
- 35 euros (2019-07-03)
- 28 euros (2018-04-24)
- 40 euros (2019-01-23)
- 60 euros (2018-10-16)
- The highest recorded price for a coin with a higher condition (90) was 260 euros, indicating that there is a market willing to pay high prices for coins in good condition.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, which is relatively low compared to the average hammer price.
- The average starting price of 45.88 euros also suggests that there is room for the hammer price to be significantly higher.

4. Recent Trends:
- The price trend in recent auctions shows that coins with similar conditions have had hammer prices ranging between 30 and 60 euros, with some higher peaks.

Based on these factors, an estimated maximum purchase price for this coin could be between 70 and 90 euros, considering that the condition is good and the price history suggests there is demand for coins in this state.

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