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 80 (MS+), indicating that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Auction Prices: By observing the hammer prices of coins with similar conditions (around 80), we can see that the hammer prices have varied, but there are examples of auctions reaching up to 220 euros for conditions of 80.

3. Average Hammer Price: The average hammer price for this coin is 166.4 euros, providing a solid basis for estimating the price.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 180 to 220 euros.

5. Starting Price: The starting price of 175 euros is a good indicator of what is expected to be obtained in the auction, but the hammer price can be significantly higher.

Taking all these factors into account, an estimated maximum purchase price for this coin could be between 220 and 250 euros, considering that the condition is favorable and there is a trend for hammer prices to be higher in recent auctions.

Therefore, a reasonable maximum purchase price could be 250 euros.