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 70 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for similar coins in the past is 39.8 euros.
- The coin has been auctioned 72 times, of which it has sold 61 times, indicating good demand.
- Previous hammer prices for coins with a similar condition (70) have varied, but there are examples of auctions reaching up to 95 euros (in the case of a condition of 75).

3. Starting Price and Estimated Price:
- The starting price is 30 euros, and the estimated price is 50 euros. This suggests that the seller expects considerable interest in the coin.

4. Recent Trends: In the most recent auctions, hammer prices for coins with a condition of 70 have been in the range of 20 to 30 euros, but there are also examples of higher hammer prices.

Based on these factors, an estimated maximum purchase price could be in the range of 50 to 70 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate.

Therefore, a reasonable maximum purchase price could be 70 euros.