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 price compared to coins in lower conditions.

2. Auction History:
- The average hammer price for similar coins has been 40.5 euros.
- In previous auctions, coins with a similar condition (95) have reached hammer prices of up to 110 euros, although this has not occurred every time.
- The last auction of a similar coin with a condition of 90 had a hammer price of 80 euros.

3. Starting Price: The starting price is 25 euros, which may attract more bidders, but the final price could be significantly higher.

4. Sales Trends: Out of the 36 times this coin has been auctioned, it has sold 26 times, indicating good demand.

5. Previous Prices: In recent auctions, the hammer price has varied, but it has reached up to 80 euros for coins in similar conditions.

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 there is a price history that supports this estimate. A price of 80 euros could be a reasonable target, given the auction history and current condition.