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 the best possible condition.

2. Current Starting Price and Previous Prices: The current starting price is 1500 euros. In previous auctions, hammer prices have varied significantly, with a maximum price of 4400 euros in a recent auction.

3. Average Hammer Price: The average hammer price for this coin has been 2644.38 euros, suggesting that, in general, buyers are willing to pay more than the starting price.

4. Auction Trends: The coin has been auctioned 10 times, of which 9 have sold. This indicates good demand and sustained interest in the coin.

5. Condition in Previous Auctions: In previous auctions, coins with similar conditions (70 and 80) have reached hammer prices of up to 3600 euros. The condition of 85 in a recent auction also suggests that there is potential for high prices for coins in good condition.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 3000 to 3500 euros, considering that the current condition is good and there is a history of hammer prices that supports this estimate. However, since the starting price is 1500 euros, it is likely that buyers will be willing to bid more, especially if there is interest in the coin.