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 90 (EF), indicating that it is in quite good shape. This generally translates to a higher value compared to coins with lower conditions.

2. Current Starting Price and Previous Prices: The current starting price is 2500 euros. In previous auctions, hammer prices have varied, but there are examples of coins with similar conditions that have sold for prices ranging from 600 to 3300 euros, depending on the condition and demand at that time.

3. Sales Trends: Out of the 45 times this coin has been auctioned, it has sold 38 times, indicating a good sales rate. This suggests that there is consistent interest in the coin.

4. Average Hammer Price: The average hammer price for similar coins is 976.43 euros, which can serve as a benchmark.

5. Recent Hammer Prices: In the most recent auctions, hammer prices have varied, but there are examples of coins in similar conditions that have sold for prices above 1000 euros.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 2000 to 3000 euros, considering that the condition is good and there is interest in the coin. However, given the starting price of 2500 euros, a realistic hammer price could be closer to 2500 to 2800 euros, depending on the competition in the auction.