To estimate a maximum purchase price for the coin in question, we can consider several factors:

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. Historical Prices: By looking at previous auction prices for coins with similar conditions, we can see that prices have varied. For example:
- In 2020, a coin with a condition of 85 sold for 280 euros.
- In 2022, a coin with a condition of 75 sold for 340 euros.
- In 2023, a coin with a condition of 95 sold for 600 euros.

3. Starting Price and Average Hammer Price: The current starting price is 375 euros, and the average hammer price in the past has been 319.83 euros. This suggests that the starting price is relatively high compared to the average hammer price.

4. Market Trends: Since the coin has been auctioned 37 times in the past and has had a sell-through rate of 97% (36 out of 37), this indicates a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 400 to 450 euros, considering that a condition of 70 may not reach the highest prices, but still holds significant value in the market.

Therefore, a reasonable maximum purchase price could be 450 euros.