To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Condition: The coin has a condition of 95 (EF+), which indicates that it is in very good shape. This generally increases its value compared to coins in lower condition.

2. Auction history:
- In the auction of October 2022, the coin sold for 335 euros with a condition of 80.
- In March 2023, it sold for 360 euros with a condition of 90.
- The average hammer price in the past has been 347.5 euros.

3. Current starting price: The starting price is 350 euros, which is slightly higher than the previous average hammer price, but given that the condition is better, this may be justifiable.

4. Supply and demand: The coin has sold on all previous occasions, and there have been no failed sale attempts, suggesting that there is consistent interest in this coin.

Taking these factors into account, an estimated maximum purchase price could be slightly above the previous highest hammer price (360 euros), given that the condition is better.

Therefore, a reasonable maximum purchase price could be 375 to 400 euros. This would allow for competitive bidding in the auction without exceeding the historical value of the coin too much.