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

1. Current Condition: The coin has a condition of 75 (MBC). This is an important factor, as coins in better condition tend to reach higher prices.

2. Historical Prices: By looking at previous auction prices for coins with similar conditions, we can see that the hammer price has varied. For example:
- In previous auctions, coins with conditions ranging from 80 to 95 have had hammer prices ranging from 220 to 650 euros.
- The last auction of a coin with a condition of 95 reached a hammer price of 620 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 340.59 euros. This suggests that the market is willing to pay close to this price.

4. Recent Trends: In the most recent auctions, hammer prices have shown a trend of increasing, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 400 to 500 euros. This is because, although the condition is not the highest, the interest in coins of this type and the recent price trends suggest that it could reach a higher price than the historical average.

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