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 80 (MS+), indicating that it is in fairly good shape, but not the best possible condition.

2. Previous Auction Prices:
- The average hammer price for coins with a similar condition (80) has been approximately 220-270 euros in recent auctions.
- In previous auctions, coins with a condition of 80 have reached hammer prices of up to 750 euros, although this was for a condition of 90.

3. Starting Price and Average Starting Price:
- The current starting price is 150 euros, which is below the average starting price of 181.04 euros. This suggests that there is potential for the hammer price to be higher.

4. Sales Trends: The coin has been sold in 92.86% of the auctions it has participated in, indicating good demand.

5. Previous Estimates: In previous auctions, the estimated price for coins with a similar condition has ranged from 200 to 350 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 250 to 300 euros. This is based on the current condition, previous hammer prices, and sales trends. However, it is important to note that the final price may vary depending on competition in the auction and the interest of collectors.