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-), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By looking at previous auction prices for coins with similar conditions, we can see that prices have varied. For example:
- In 2022, a coin with a condition of 85 was auctioned for 460 euros.
- In 2021, a coin with a condition of 80 was auctioned for 290 euros.
- In 2020, a coin with a condition of 80 was auctioned for 230 euros.

3. Average Auction Price: The average auction price for this coin is 331.89 euros, which gives us a good reference for the market value.

4. Starting Price and Average Starting Price: The current starting price is 175 euros, and the average starting price is 182.29 euros. This suggests that the market is willing to accept higher prices than the starting price.

5. Auction Trends: The coin has been auctioned 50 times, with a high sales percentage (46 out of 50). This indicates a consistent demand.

Based on these factors, an estimated maximum purchase price could be in the range of 400 to 500 euros, considering that the condition is good and that previous auction prices for similar conditions have reached higher figures.

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