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 among the best qualities (FDC).

2. Auction History:
- The average hammer price for similar coins has been 56.41 euros.
- In the past, coins with similar conditions (around 70-80) have sold in a price range that varies considerably, but some have reached hammer prices of up to 180 euros for higher conditions (95).

3. Starting Price and Estimates:
- The current starting price is 15 euros, which is relatively low compared to the average hammer price.
- The average starting price for similar coins is 42.65 euros.

4. Recent Trends:
- Recent auctions show that coins with similar conditions have had hammer prices ranging from 25 to 70 euros, depending on demand and quality.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 70 to 100 euros. This is based on the fact that, although the condition is not the highest, the price history and current demand suggest it could reach a higher price than the average hammer price, especially if there is interest in the auction.

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