To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Condition: The coin has a condition rating of 70 (VF-), indicating that it is in acceptable condition, but not among the best qualities. This affects the price, as coins in better condition tend to fetch higher prices.

2. Auction History:
- It has been auctioned 8 times in the past, of which it has sold 4 times. This suggests there is moderate interest in the coin.
- Previous hammer prices have varied, but the average hammer price in auctions where it sold is approximately 27 euros.
- In past auctions, the estimated price has ranged between 25 and 45 euros, but the highest recorded hammer price was 30 euros.

3. Starting Price and Average Hammer Price: The current starting price is 25 euros, and the average hammer price is 27 euros. This suggests that the market is willing to pay a little more than the starting price, but not much more.

4. Price Trends: Given that the estimated price in previous auctions has been up to 45 euros, but the highest hammer price has been 30 euros, it is reasonable to assume that interest in this coin has not increased significantly since then.

Based on these factors, an estimated maximum purchase price could be around 30-35 euros. This is based on the history of hammer prices and the condition of the coin. Therefore, a reasonable maximum purchase price could be 35 euros.