To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in an acceptable state, but not of the highest quality.

2. Previous Auction Prices: By observing the auction prices of coins with a similar condition (70), we can see that they have varied, but generally sold between 35 and 70 euros in previous auctions. For example:
- In several auctions, coins with a condition of 70 have been sold at prices like 35, 50, 60, and even 70 euros.

3. Average Auction Price: The average auction price for this coin is 76.12 euros, but this includes coins of different conditions. Given that the condition of the coin in question is 70, it is reasonable to adjust our expectations to a lower range.

4. Starting Price: The starting price is 15 euros, indicating that the seller expects moderate interest in the coin.

5. Sales Trends: The coin has been auctioned 56 times, of which 48 have resulted in sales. This suggests that there is an active market for this coin.

### Estimated Maximum Purchase Price
Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 60 to 70 euros. This range considers the current condition, previous auction prices for similar coins, and the general interest in the coin.

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