To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Condition: The coin has a condition rating of 80 (MBC+), indicating that it is in quite good shape. This generally translates to a higher value compared to coins with lower conditions.

2. Auction History:
- It has been auctioned 8 times in the past, of which it has sold 6 times.
- The average hammer price in previous auctions is 27.2 euros, giving us an idea of the value that buyers are willing to pay.
- In the last auction (2023-01-31), the coin sold for 55 euros, which is a good indicator of its current value.

3. Starting Prices and Estimates:
- The current starting price is 25 euros, which is relatively low compared to previous hammer prices.
- Estimated prices in previous auctions have varied, but have reached up to 65 euros in some cases.

4. Trends:
- The overall trend seems to be that the hammer price has been increasing, especially in the last auction where it reached 55 euros.

Based on this data, an estimated maximum purchase price could be in the range of 55 to 65 euros, considering that the last sale was at 55 euros and that estimated prices in previous auctions have reached up to 65 euros.

Therefore, a reasonable maximum purchase price could be 60 euros.