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

1. Condition: The coin to be auctioned has a condition of 80 (MBC+), which is a positive factor. In comparison, coins with higher conditions tend to reach higher prices.

2. Previous auction prices: By observing previous hammer prices, we can see that in recent auctions, prices have varied. For example, in the March 2023 auction, a coin with a condition of 95 was sold for 2000 euros, and in another auction in 2022, a coin with a condition of 75 was sold for 1350 euros.

3. Starting price and average hammer price: The current starting price is 1600 euros, and the average hammer price in previous auctions is 1139.09 euros. However, the starting price may be an indicator of the seller's expectations regarding the coin's value.

4. Price trends: The general trend appears to be upward, as hammer prices have been increasing in the most recent auctions.

Taking these factors into account, an estimated maximum purchase price could be in the range of 1800 to 2200 euros. This is based on the coin's condition, previous hammer prices, and the current starting price. A price of 2000 euros could be a reasonable target, given that it has been reached in recent auctions for coins in better condition.