To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current starting price: 1100 euros.
2. Average hammer price in the past: 1400 euros.
3. Current condition: 80 (MBC+), which is quite a good condition.
4. Auction history:
- In 2016, it was auctioned with a starting price of 900 euros and hammered at 900 euros.
- In 2014, it was auctioned with a starting price of 800 euros and hammered at 1000 euros.
- In 2021, a hammer price of 1200 euros was estimated with a condition of 75.
- In 2021, a hammer price of 2500 euros was estimated with a condition of 95, but it did not sell.
- In 2024, it was auctioned with a starting price of 1600 euros and hammered at 2000 euros with a condition of 85.

Given that the current condition of the coin is 80, which is better than 75 and comparable to 85, we can infer that the hammer price could be in a similar range or slightly higher than previous auctions.

### Maximum Purchase Price Estimate:
- Considering the average hammer price of 1400 euros and the auction history, a reasonable hammer price could be between 1400 and 1600 euros, given that the condition is good and there is interest in the coin.
- Since the starting price is 1100 euros, a maximum purchase price could be slightly higher than the average hammer price, but not so much as to exceed the starting price of the next auction.

Therefore, an estimated maximum purchase price could be 1600 euros. This is based on the trend of previous prices and the current condition of the coin.