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), 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 is 83 euros.
- The condition of the coins auctioned in the past varied, but there are examples of coins with similar conditions (70-80) that have sold for prices ranging from 25 to 380 euros, depending on the condition and demand.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, which is relatively low compared to the average hammer price of 83 euros.
- The average starting price of 45.22 euros also suggests that there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, hammer prices have varied, but there is a pattern that coins with conditions of 70-80 have reached hammer prices around 40-70 euros.

Based on these factors, an estimated maximum purchase price for this coin could be around 70-80 euros, as this price reflects its condition and the sales history of similar coins. However, it is important to keep in mind that the final price may vary depending on the competition in the auction and the specific demand at that time.