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

1. Condition: The coin has a condition of 70 (VF-), indicating that it is in relatively good shape. This can positively influence its value.

2. Auction History:
- It has been auctioned 8 times in the past, of which it has sold 5 times. This suggests there is consistent interest in the coin.
- The average hammer price in previous auctions is 287 euros, which can serve as a good indicator of market value.

3. Previous Starting and Hammer Prices:
- In the most recent auction (2020), the starting price was 200 euros and the hammer price was 320 euros. This shows that the coin can reach prices above its starting price.
- In other auctions, hammer prices have varied, but they have generally been above the starting price.

4. Current Starting Price: The current starting price is 250 euros, which is slightly higher than the average starting price of 232.86 euros.

Given that the average hammer price is 287 euros and considering that the coin has a condition of 70, an estimated maximum purchase price could be set in a range that reflects both the interest in the coin and its condition.

Estimated Maximum Purchase Price:
We could consider a maximum purchase price around 300-320 euros, as this aligns with previous hammer prices and reflects reasonable interest in the coin, taking into account its condition and auction history.

Therefore, an estimated maximum purchase price could be 320 euros.