To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the starting price, current condition, and previous auction hammer prices.

1. Current Condition: The coin has a condition of 85 (ebc-), indicating that it is in fairly good shape, but not the best possible condition.

2. Previous Hammer Prices:
- In 2020, with a condition of 85, it sold for 1500 euros.
- In 2019 and 2018, with conditions of 95, the hammer prices were 3200 and 3000 euros, respectively.
- In 2021, with a condition of 90, it did not sell, but the estimated price was 1500 euros.
- In 2022, with conditions of 80 and 70, the hammer prices were 850 and 405 euros, respectively.

3. Average Hammer Price: The average hammer price for this coin is 1944.38 euros, suggesting that, in general, coins of this reference tend to sell for relatively high prices.

4. Current Starting Price: The starting price is 1500 euros, which is a reasonable starting point.

Given that the coin's condition is 85 and considering the previous hammer prices, an estimated maximum purchase price could be set in a range between the starting price and the average hammer price.

Taking all these factors into account, a reasonable maximum purchase price could be:

Estimated maximum purchase price: 1800 euros.

This price reflects a value above the starting price but below the average hammer price, considering the current condition of the coin.