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

1. Coin 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. Auction History:
- The average hammer price for this coin is 242.21 euros.
- In previous auctions, hammer prices have varied significantly, but some relevant examples are:
- In 2020, a coin with a similar condition (80) was sold for 65 euros.
- In 2018, another coin with a condition of 80 sold for 40 euros.
- In 2023, a coin with a condition of 80 was auctioned for 75 euros.

3. Starting Price and Recent Hammer Prices:
- The current starting price is 30 euros, which is relatively low compared to the average hammer price.
- Given that the average hammer price is significantly higher than the starting price, this suggests there is potential for the coin to sell for a higher price.

4. Auction Trends: The coin has been auctioned 77 times, with a high sales percentage (71 out of 77). This indicates a consistent interest in this coin, which may influence the price.

Based on these factors, an estimated maximum purchase price could be in the range of 200 to 300 euros, considering that the average hammer price is 242.21 euros and that the coin's condition is good. However, given the hammer price history, a more conservative price might be around 200 euros, while a more optimistic price could reach up to 300 euros if there is active competition in the auction.