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 rating of 70 (VF-), indicating that it is in relatively good shape, but not the best possible condition.

2. Previous Prices: Looking at past auction prices, we can see that the coin has reached auction prices of up to 160 euros in the past (in 2016) and 120 euros in 2022. However, it has also had lower auctions, such as 17 euros in 2020.

3. Average Auction Price: The average auction price for this coin is 70.08 euros, which can serve as a good reference point.

4. Starting Price and Average Starting Price: The current starting price is 18 euros, and the average starting price is 44.23 euros. This suggests that the market is willing to accept higher prices than the starting price.

5. Recent Trends: In the most recent auctions, the hammer prices have been higher, which could indicate an upward trend in interest for this coin.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 80 to 100 euros. This is based on the current condition, previous auction prices, and recent market trends.

Therefore, a reasonable maximum purchase price could be 90 euros.