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+), indicating that it is in relatively good shape, but not the best possible condition.

2. Current Starting Price and Previous Prices: The current starting price is 1400 euros. In previous auctions, the average hammer price has been 1219.91 euros, suggesting that buyers are generally willing to pay a bit more than the starting price.

3. Price Trends: Looking at previous hammer prices for coins with similar conditions (80 and 75), prices have varied, but generally, coins with a condition of 80 have reached hammer prices ranging from 1100 to 1350 euros in recent auctions.

4. Sales Expectations: Given that there is an auction scheduled in the coming days, demand may increase, which could drive up the hammer price.

5. Analysis of Recent Hammer Prices: In the most recent auctions, hammer prices for coins with a condition of 80 have been around 1350 euros, and in some cases, even higher.

Based on these factors, an estimated maximum purchase price could be between 1350 and 1500 euros, considering that the starting price is 1400 euros and that there is a trend for hammer prices to exceed the starting price in previous auctions.

Therefore, a reasonable maximum purchase price could be 1500 euros.