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 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. Auction History:
- The average hammer price for coins with a similar condition (80) in the past has been approximately 140-180 euros.
- The last auction of a coin with a condition of 80 had a hammer price of 140 euros.
- Overall, hammer prices for coins with a condition of 80 have ranged between 110 and 180 euros in previous auctions.

3. Starting Price: The starting price of 150 euros is a good indicator of the seller's expectations, but it does not necessarily reflect the final hammer price.

4. Sales Trends: The coin has been auctioned 43 times, of which 41 have sold, indicating good demand and a history of successful sales.

5. Comparison with Previous Prices: In previous auctions, coins with similar conditions have had hammer prices that vary, but they have generally sold above the starting price.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 160 to 180 euros. This is based on the hammer price history for coins of similar condition and the expectation that demand will remain steady.