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 relatively good shape.

2. Previous Auction Prices:
- In previous auctions with a condition of 70, the hammer prices have been 55 (in 2020) and 105 (in 2023).
- There is also a hammer price of 78 in an auction with unspecified condition, but it could be relevant.

3. Price Trends:
- The average hammer price for this coin is 60.87 euros, suggesting that, in general, buyers are willing to pay around this amount.
- The current starting price is 30 euros, which is quite low compared to previous hammer prices.

4. Estimation:
- Given that the condition is 70 and considering the previous hammer prices, a reasonable maximum purchase price could be between 70 and 105 euros, depending on the competition in the auction and the interest of collectors.

Conclusion: An estimated maximum purchase price for this coin could be approximately 90 euros. This is based on the current condition and previous hammer prices, suggesting that it is a competitive and attractive value for bidders.