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 80 (MS+), indicating that it is in relatively good shape. This can positively influence its price.

2. Historical Prices: By looking at previous auction prices for coins with similar conditions, we can see that prices have varied. For example:
- In 2023, a coin with a condition of 80 sold for 160 euros.
- In 2022, a coin with a condition of 80 sold for 130 euros.
- In 2020, a coin with a condition of 80 sold for 140 euros.

3. Average Auction Price: The average auction price for this coin is 169.36 euros, which is also a good indicator of the expected value.

4. Starting Price: The starting price is 150 euros, suggesting that the seller expects a reasonable price.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, especially for coins in good condition.

Taking all these factors into account, an estimated maximum purchase price could be around 180-200 euros. This is based on the average auction price and recent trends, as well as the condition of the coin. However, it is important to remember that the final price may vary depending on competition in the auction and the interest of other buyers.