To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Condition: The coin has a condition of 85 (ebc-), indicating that it is in quite good shape. This suggests that its value should be in the upper range of previous auction prices.

2. Previous Auction Prices: By observing previous auction prices for coins with similar conditions, we can see that prices have varied. For example:
- In 2020, a coin with a condition of 85 was auctioned for 320 euros.
- In 2021, another coin with a condition of 85 was auctioned for 440 euros.
- In 2022, a coin with a condition of 85 was auctioned for 420 euros.

3. Average Auction Price: The average auction price for this coin is 300.43 euros, providing an additional reference point.

4. Starting Price: The current starting price is 360 euros, indicating that the seller has expectations of a higher price.

5. Market Trends: Since the coin has been auctioned 44 times and has had a high sales percentage (40 out of 44), this suggests there is consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 400 and 450 euros, considering that the condition is good and that previous auction prices for similar conditions have reached figures in that range.

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