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 fairly good shape, but not the best possible condition.

2. Auction History:
- The average hammer price in previous auctions is 386.12 euros.
- The coin has been auctioned 14 times, of which it has sold 8 times, indicating a sell-through rate of 57.14%. This suggests that there is interest in the coin, but also that there is a 42.86% chance it has not sold, which may influence the perception of its value.

3. Previous Prices:
- Previous hammer prices have varied, but there is a notable price of 950 euros for a condition of 90, indicating that the value can increase significantly with better condition.
- Overall, hammer prices for similar conditions (80) have ranged from 240 to 600 euros.

4. Current Starting Price: The starting price is 150 euros, which is relatively low compared to the average hammer price.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 400 euros, considering that the condition is good but not excellent, and that the interest in the coin seems to be moderate. A price of 350 euros could be a reasonable benchmark for a competitive offer.