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

1. Current Condition: The coin has a condition rating of 80 (MS+). This is an important factor, as coins in better condition tend to reach higher prices.

2. Previous Prices: By observing the hammer prices of coins with similar conditions (around 80-85), we can see that the hammer prices have varied, but generally, coins with a condition of 80 have reached hammer prices ranging from 260 to 300 euros in recent auctions.

3. Starting Price and Average Hammer Price: The current starting price is 325 euros, and the average hammer price in the past has been 297.25 euros. This suggests that the starting price is slightly higher than the average of what has been sold previously.

4. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have shown an increase, reaching up to 440 euros in some cases. However, this may depend on the demand and supply at the time of the auction.

Based on these factors, an estimated maximum purchase price for this coin could be between 350 and 400 euros. This is based on recent price trends and the condition of the coin. If the auction is competitive, it is possible that the hammer price will approach this range.