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

1. Current Condition: The coin has a condition rating of 30 (BC+), indicating that it is not in the best condition. This generally reduces its value compared to coins in better condition.

2. Auction History:
- The average hammer price for this coin in the past has been 187.06 euros.
- The condition of coins auctioned in the past has varied, but there are examples of coins with higher conditions that have reached significantly higher prices (for example, a coin with a condition of 95 was sold for 875 euros).

3. Recent Starting and Hammer Prices:
- The current starting price is 15 euros, which is relatively low.
- In previous auctions, hammer prices have varied, but there are examples of coins with similar conditions that have sold for prices ranging between 15 and 30 euros.

4. Market Trends: Since the coin has been auctioned 40 times and has had a sell-through rate of 97.5%, this suggests that there is consistent interest in this coin, which may influence its price.

Based on these factors, an estimated maximum purchase price for this coin could be between 30 and 50 euros. This takes into account its current condition and the auction price history, as well as the interest in the coin. However, since the starting price is 15 euros, it may be possible to acquire it for a lower price if there is not much competition in the auction.