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), indicating that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The coin has been auctioned 6 times, of which it has sold 5 times. This indicates good demand.
- The average hammer price in previous auctions is 69.4 euros, suggesting that buyers are willing to pay a considerable price for this coin.
- In the most recent auction (2023-02-16), the coin was estimated at 75 euros and sold for 70 euros, reinforcing the idea that the price range is around 70-75 euros for similar conditions.

3. Price Trends:
- In the auction on 2023-01-31, the coin was estimated at 50 euros and sold for 200 euros, indicating that there may be significant interest in coins of good condition, although this case seems to be an exception.
- The 2020 auction shows a hammer price of 29 euros, which is considerably lower, but the condition was 70.

4. Starting Price and Average Starting Price: The current starting price is 30 euros, and the average starting price is 28 euros. This suggests that the seller has moderate expectations, but market interest could lead to a higher hammer price.

Based on these factors, an estimated maximum purchase price for this coin, considering its condition and price history, could be between 70 and 80 euros. However, given the demonstrated interest in previous auctions, a reasonable maximum purchase price could be 80 euros.