To estimate a maximum purchase price for the coin in question, we can analyze the provided data and 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. Auction History:
- It has been auctioned 9 times in total, of which 7 have sold. This indicates a consistent interest in the coin.
- Previous hammer prices for coins with similar conditions (70 and 75) have varied, but we can observe that in recent auctions, the hammer price for a coin with a condition of 70 was 90 euros in 2022.

3. Starting and Hammer Prices:
- The average starting price is 300.82 euros, but this can be misleading if we consider that the actual hammer price may be much lower, especially for coins in VF- condition.
- The current starting price is 50 euros, which suggests that the auction house expects moderate interest.

4. Price Trends:
- In previous auctions, hammer prices for coins with a condition of 70 have been around 90 euros, while for higher conditions (like 80 or 90), prices have been significantly higher.

Based on these factors, an estimated maximum purchase price for the coin in condition 70 could be in the range of 90 to 150 euros, considering that interest in the coin may vary and that the hammer price can be influenced by demand at the auction.

Therefore, a reasonable estimated maximum purchase price could be 150 euros.