To estimate a maximum purchase price for the coin in question, we can analyze the provided data, taking into account the current condition of the coin (70, VF-) and the hammer prices from previous auctions.

1. Condition: The coin has a condition of 70, which is considered VF-. This suggests that its state is acceptable but not excellent. Generally, coins in better condition tend to reach higher prices.

2. Previous hammer prices: Looking at the hammer prices of coins with similar conditions:
- In 2020, a coin with a condition of 70 was auctioned for 110 euros.
- In 2013, a coin with a condition of 75 was auctioned for 462.4 euros.
- In 2019, a coin with a condition of 80 was auctioned for 340 euros.

3. Price trends: The average hammer price for previous auctions is 320.14 euros, indicating that, in general, coins of this reference tend to reach prices in that range.

4. Starting price: The current starting price is 300 euros, which is a good starting point. However, since the average hammer price is higher, it is reasonable to expect that the final hammer price will be higher.

5. Estimation: Considering all these factors, an estimated maximum purchase price could be in the range of 350 to 400 euros, taking into account that the condition is VF- and that there is a price history suggesting that coins in similar conditions have reached higher prices.

Therefore, an estimated maximum purchase price for this coin could be approximately 375 euros.