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 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 this coin is 66.45 euros.
- In previous auctions, the hammer price has varied, with a maximum of 130 euros in a recent auction (2021-06-03) for a coin in condition 80.
- The last auction with a condition of 80 reached a hammer price of 95 euros.

3. Starting Price: The current starting price is 50 euros, which may influence bidder interest.

4. Price Trends: Observing previous hammer prices, it seems that coins with similar condition (70) have reached hammer prices ranging between 40 and 75 euros in the past.

Given that the condition of the coin is 70 and considering the price history, an estimated maximum purchase price could be in the range of 75 to 90 euros. This is based on the fact that, although the average hammer price is 66.45 euros, there are examples of higher hammer prices that could be achieved by a coin in good condition.

Therefore, a reasonable estimated maximum purchase price could be 85 euros.