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

1. Coin Condition: The coin has a condition of 30 (BC+), which indicates that it is not in the best condition. This generally negatively affects its value compared to coins in better condition.

2. Previous Auction Prices: By observing the hammer prices of coins with similar conditions, we can see that prices have varied. For example:
- In 2019, a coin with a condition of 25 sold for 30 euros.
- In 2020, a coin with a condition of 70 sold for 65 euros.
- In 2022, a coin with a condition of 70 sold for 100 euros.

3. Average Hammer Price: The average hammer price for this coin is 84.45 euros, indicating that, in general, coins of this reference tend to sell for higher prices.

4. Starting Price: The starting price is 40 euros, which can be a good indicator of the expected sale.

5. Market Trends: Given that the coin has been auctioned 103 times and has had a high sales percentage (88 out of 103), this suggests that there is a constant interest in this coin.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 50 to 70 euros, considering its condition and the hammer prices of similar coins in the past. This allows for some margin for competition in the auction, but also reflects the condition of the coin.