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 (MBC+), indicating that it is in quite good shape. This suggests that its value should be in the upper range of previous auctions.

2. Auction History:
- The average hammer price from previous auctions is 270.71 euros.
- The coin has been auctioned 8 times, of which it has sold 7 times, indicating good demand.
- The average starting price is 176.43 euros, but the current starting price is 150 euros, which is lower than the average.

3. Previous Prices:
- In past auctions, hammer prices have varied, but there are examples of auctions reaching up to 345 euros (2017) and 340 euros (2022) for coins in similar conditions.
- The last auction with a condition rating of 80 had a hammer price of 340 euros.

4. Market Trends: Given that the coin will be auctioned in the near future and has shown consistent interest in the past, it is reasonable to assume that the price could be on the rise.

Based on these factors, an estimated maximum purchase price could be in the range of 300 to 350 euros, considering that the condition is good and that interest in the coin appears to be solid. Therefore, a reasonable maximum purchase price could be 350 euros.