To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Starting price: 350 euros.
2. Current condition: 75 (MBC), which is a good but not excellent condition.
3. Auction history: The coin has been auctioned 2 times in the past and has sold on both occasions. This indicates a consistent interest in the coin.
4. Average hammer price: 375 euros, which is the average price it has sold for in the past.
5. Previous hammer price: In the November 2020 auction, the coin sold for 340 euros with a condition of 80, which is better than the current one.

Given that the current condition is slightly lower than that of the previous auction, and considering that the average hammer price is 375 euros, an estimated maximum purchase price could be set in a range that reflects the condition and interest in the coin.

Taking all these factors into account, an estimated maximum purchase price could be around 350-360 euros. This allows for some competition in the auction, but also reflects the current condition of the coin.