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 relatively good shape, but not of the highest quality (FDC).

2. Historical Prices: Looking at previous auction prices, we can see that coins with similar conditions have reached varying auction prices. For example:
- In 2020, a coin with a condition of 95 was auctioned for 650 euros.
- In 2019, a coin with a condition of 80 was auctioned for 242 euros.
- In 2022, a coin with a condition of 90 was auctioned for 380 euros.

3. Average Auction Price: The average auction price for this coin is 306.18 euros, which can serve as a reference point.

4. Starting Price: The current starting price is 350 euros, indicating that the seller expects a higher price than the historical average.

5. Sales Trends: The coin has been auctioned 32 times, of which it has sold 28 times, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 400 to 500 euros. This is because, although the condition is not the highest, the interest in the coin and the starting price suggest that it could reach a higher price than the historical average, especially if there is competition in the auction.

Therefore, a reasonable maximum purchase price could be 450 euros.