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-), which indicates that it is in an acceptable state, but not among the best qualities. This can influence the price, as coins in better condition tend to reach higher prices.

2. Previous Auction Prices: By observing previous hammer prices for coins with similar conditions (70 and 80), we can see that the hammer price for coins with a condition of 70 has ranged between 100 and 140 euros. For example:
- In 2020, a coin with a condition of 70 was sold for 100 euros.
- In 2022, a coin with a condition of 80 was sold for 150 euros.

3. Starting Price and Average Hammer Price: The current starting price is 120 euros, and the average hammer price in previous auctions is 130.92 euros. This suggests that the hammer price could be in a similar range or slightly above the starting price.

4. Recent Trends: In the most recent auctions, hammer prices have been around 150 euros for similar conditions, indicating an upward trend.

Based on these factors, an estimated maximum purchase price could be around 140-160 euros. This is based on the analysis of previous hammer prices and the current condition of the coin.

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