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 of 75 (MBC), indicating that it is in fairly good shape, but not the best possible condition.

2. Previous Prices: Looking at previous auction prices for coins with similar conditions, we can see that:
- In past auctions, coins with conditions ranging from 70 to 80 have reached hammer prices between 180 and 400 euros.
- The last auction with a condition of 75 had a hammer price of 380 euros.

3. Starting Price and Average Hammer Price: The current starting price is 350 euros, and the average hammer price in the past has been 278.16 euros. This suggests that the starting price is relatively high compared to the average hammer price.

4. Auction Trends: The coin has been auctioned 32 times and has had a 100% sell-through rate, indicating a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 380 to 450 euros, considering that the condition is good and there is a history of hammer prices that supports this estimate. However, since the starting price is 350 euros, it may be wise not to exceed this limit unless one is confident that demand will be high.

Therefore, a reasonable maximum purchase price could be 400 euros.