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

1. Current Condition: The coin has a condition rating of 75 (MBC), indicating that it is in relatively good shape. This can positively influence its price.

2. Historical Prices: By looking at previous auction prices, we can see that the coin has reached auction prices of up to 440 euros in similar conditions. However, most auction prices fall within a lower range, between 50 and 260 euros.

3. Average Auction Price: The average auction price for this coin is 129.68 euros, which can serve as a good reference point.

4. Starting Price and Average Starting Price: The current starting price is 70 euros, and the average starting price is 79.34 euros. This suggests that the market is willing to accept prices in this range.

5. Recent Trends: In the most recent auctions, the hammer prices have been relatively high, which could indicate an increase in demand.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 150 to 200 euros. This is based on the average auction price and the trend of prices in recent auctions, as well as the condition of the coin.

Therefore, a reasonable maximum purchase price could be 200 euros.