To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the current condition, previous auction prices, as well as the general price trend.

1. Condition: The coin has a condition of 85 (ebc-), which indicates that it is in quite good shape. This is relevant because coins in better condition tend to fetch higher prices.

2. Previous Prices:
- The average hammer price for similar coins has been 2221.88 euros.
- In previous auctions, we have seen hammer prices that varied, but some relevant examples are:
- 2000 euros for a coin with a condition of 85.
- 2400 euros for a coin with unspecified condition, but in a similar range.
- 3400 euros for a coin with unspecified condition, but in a higher range.

3. Starting Price: The current starting price is 2800 euros, which is higher than the average starting price of 1384.21 euros, suggesting that the seller has high expectations for this auction.

4. Trends: Looking at previous auctions, it seems that coins with similar conditions have reached hammer prices ranging from 2000 to 2400 euros, with some exceptional cases exceeding 3000 euros.

Based on these points, an estimated maximum purchase price could be set in a range between 2400 and 3000 euros, considering that the condition is good and the starting price is relatively high. However, since the starting price is 2800 euros, a reasonable maximum purchase price could be approximately 3000 euros. This would allow for competitive bidding in the auction without exceeding a limit that could be considered excessive based on historical data.