To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition rating of 30 (BC+). This is relatively low compared to other coins that have been auctioned, which may affect its value.

2. Auction History:
- The average hammer price for similar coins is 31.43 euros.
- In previous auctions, hammer prices have varied, with some reaching up to 50 euros, but there are also examples of lower hammer prices, such as 15 euros.

3. Starting Price: The starting price is 25 euros, indicating that the seller expects a minimum of 25 euros, but this does not guarantee that it will sell at that price.

4. Sales Trends: Out of the 14 times it has been auctioned, it has sold on 10 occasions, suggesting there is moderate interest in this coin.

5. Comparison with Previous Prices:
- In recent auctions, the hammer price has ranged between 15 and 50 euros, depending on the condition and other factors.

Given that the condition of this coin is 30 (BC+), which is below the average of coins that have sold in the past, and considering the average hammer price, an estimated maximum purchase price could be set in a more conservative range.

Estimated Maximum Purchase Price:
Taking all these factors into account, a reasonable maximum purchase price could be between 25 to 30 euros. This is based on the starting price and the history of hammer prices, adjusted for the current condition of the coin.