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

1. Current Condition: The coin has a condition of 80 (MBC+), which indicates that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History:
- The average hammer price for this coin in the past is 160.25 euros.
- The condition of coins auctioned in the past varies, but there are examples of coins with similar condition (80) that have sold for prices ranging from 50 to 85 euros at auction.

3. Starting Price and Average Starting Price:
- The current starting price is 20 euros, which is quite low compared to the average hammer price.
- The average starting price is 78.66 euros, suggesting that the market is willing to pay more than the starting price.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have been in the range of 50 to 90 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 80 and 120 euros, considering that the condition is good and that the price history suggests buyers are willing to pay more than the starting price.

Therefore, a reasonable maximum purchase price could be 100 euros.