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

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

2. Previous Auction Prices:
- In previous auctions with a similar condition (85), the hammer prices have varied. For example:
- 2021-06-22: 360 €
- 2022-06-01: 460 €
- 2022-07-07: 400 €
- 2023-02-16: 380 €
- 2023-03-16: 400 €
- The highest hammer price in this condition range was 460 €.

3. Average Hammer Price: The average hammer price for this coin is 355.8 €, which is also a good indicator of the expected value.

4. Starting Price: The starting price is 325 €, suggesting that the seller has reasonable expectations about the coin's value.

5. Price Trends: Observing the trends, it seems that prices have been increasing in recent years, especially for coins in good condition.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 400 € to 460 €, considering that the condition is good and there are precedents for auctions in that range.

Therefore, a reasonable maximum purchase price could be 450 €.