To estimate a maximum purchase price for the coin in question, we will consider several factors:

1. Current Condition: The coin has a condition rating of 80 (MS+), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Historical Prices: By looking at previous auction prices for coins with a similar condition (80), we can see that they have reached hammer prices of up to 220 euros in recent auctions. For example, at the auction on October 19, 2022, a coin with a condition of 85 sold for 220 euros.

3. Average Hammer Price: The average hammer price for this coin is 158.78 euros, which provides a good reference for the expected value.

4. Starting Price: The current starting price is 150 euros, suggesting that the seller has reasonable expectations for a hammer price.

5. Sales Trends: The coin has been auctioned 30 times, of which it has sold 28 times, indicating good demand and a history of successful sales.

Taking all these factors into account, an estimated maximum purchase price could be around 200-220 euros, as this aligns with the highest hammer prices observed for coins of similar condition and the interest in the coin. However, it is important to consider that the final price may vary depending on competition in the auction and other market factors at the time of sale.