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

1. Current Grade: The coin has a grade of 80 (MS+). 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 grades, we can see that:
- In past auctions, coins with a grade of 80 have reached hammer prices of up to 170 euros (as in the auction on 2013-12-04).
- Coins with a grade of 85 have reached hammer prices of up to 320 euros (as in the auction on 2016-10-19).

3. Average Hammer Price: The average hammer price for this coin is 225.78 euros, indicating that, in general, coins of this reference tend to sell for relatively high prices.

4. Starting Price and Previous Sales: The current starting price is 60 euros, and there have been 51 previous sales, suggesting a consistent interest in this coin.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of being higher, which could indicate an increase in demand.

Based on these factors, an estimated maximum purchase price for this coin could be between 200 and 300 euros, considering that the grade is good and there is a history of hammer prices that supports this estimate. A price of 250 euros could be a reasonable starting point for an offer, given the market context and the coin's condition.