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

1. Current starting price: 1550 euros.
2. Coin condition: 80 (MBC+), which is a fairly good condition, but not the highest.
3. Auction price history:
- The average hammer price in previous auctions is 1365.75 euros.
- In recent auctions, hammer prices have varied, reaching up to 1700 euros on some occasions for coins with similar conditions.
4. Price trends: In the most recent auctions, hammer prices have shown an increase, especially for coins in good condition.

Given that the coin has a condition of 80 and considering the hammer price history, an estimated maximum purchase price could be in the range of 1700 to 1800 euros, taking into account that the starting price is 1550 euros and that interest in coins in good condition has been increasing.

Therefore, an estimated maximum purchase price could be 1800 euros.