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 rating 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 14 times, of which it has sold 8 times. This indicates considerable interest in the coin.
- Previous hammer prices for coins with similar conditions (70 and 75) have varied, but there is a hammer price of 346 euros in 2017 for a coin with unspecified condition, and 700 euros in 2023 for a coin with a condition of 80.

3. Starting and Hammer Prices:
- The current starting price is 40 euros, which is significantly lower than the average starting price of 330.36 euros and the average hammer price of 477.43 euros.
- In previous auctions, starting prices have varied, but the highest hammer price for a similar condition was 700 euros.

4. Price Trends:
- Hammer prices have shown an upward trend in recent years, especially in 2023.

Based on these factors, an estimated maximum purchase price could be set in a range that considers the interest in the coin, its condition, and previous hammer prices. Given that the most recent highest hammer price was 700 euros and considering that the current condition is 70, a reasonable maximum purchase price could be:

Estimated maximum purchase price: 500 - 600 euros.

This range takes into account the possibility that the coin could reach a higher price due to its demand and condition, but it also remains conservative compared to the highest hammer prices observed.