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 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 in the past, we can see that prices have varied. For example, in previous auctions, coins with conditions ranging from 80 to 85 have reached hammer prices between 300 and 400 euros.

3. Starting Price and Average Hammer Price: The current starting price is 325 euros, and the average hammer price in the past has been 283.35 euros. This suggests that the market is willing to pay more than the average price, especially if the condition is good.

4. Recent Trends: In the most recent auctions, hammer prices have shown an upward trend, especially for coins in good condition.

5. Price Estimates: Based on historical data, a hammer price for a coin with a condition of 80 could be in the range of 350 to 400 euros, considering there is a growing interest in quality coins.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 400 euros. This would allow for competitive bidding in the auction without exceeding the current market limits for coins of this condition.