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 coin has been auctioned 6 times, of which it has sold 5 times. This indicates a consistent interest in the coin.
- The average starting price is 163.13 euros, and the average hammer price is 272.51 euros. This suggests that, in general, coins of this reference tend to sell for a considerably higher price than their starting price.

3. Previous Prices:
- In previous auctions, hammer prices have varied significantly. For example, in 2022, a coin with a condition of 85 sold for 460 euros, while one with a condition of 70 sold for 70 euros.
- The 2016 auction shows that a coin with a condition of 75 sold for 248.64 euros, indicating that a coin with a condition of 70 could be in a lower price range, but could still reach a significant price.

4. Current Starting Price: The starting price is 90 euros, which is relatively low compared to previous hammer prices.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 200 to 300 euros, considering that the condition of the coin is a limiting factor. A more conservative price could be around 250 euros, as it is an intermediate value between the average hammer price and the price history of coins with similar conditions.

Therefore, an estimated maximum purchase price could be 250 euros.