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 rating of 80 (MBC+), indicating 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 (around 80), we can see that the average auction price has been approximately 84.29 euros. However, there have been auctions that reached higher prices, especially for better conditions.

3. Average Starting and Auction Price: The average starting price is 60.66 euros, and the average auction price is 84.29 euros. This suggests that buyers are willing to pay more than the starting price on many occasions.

4. Recent Trends: In the most recent auctions, the auction prices for coins with similar conditions have varied, but some have reached up to 125 euros. This indicates that there is potential for an increase in the auction price.

5. Supply and Demand: Given that there are 4 coins that will be auctioned in the coming days, competition may influence the final price. If there is interest in the coin, this could drive the price up.

Based on these factors, an estimated maximum purchase price for the coin could be in the range of 90 to 110 euros. This range takes into account the good condition of the coin, previous auction prices, and the potential competition in the auction.