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

1. Coin 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. Auction History:
- The average hammer price for similar coins in the past is 86.58 euros.
- The coin has been auctioned 91 times, of which 81 resulted in sales. This suggests there is consistent interest in this coin.
- Previous hammer prices for coins with similar conditions (around 80) have varied, but some have reached significant prices, such as 245 euros for a coin with a condition of 90.

3. Starting Price and Previous Prices:
- The current starting price is 40 euros, which is relatively low compared to the average hammer price.
- In previous auctions, coins with similar conditions have had hammer prices ranging from 50 to 100 euros, depending on demand and other factors.

4. Recent Trends:
- In the most recent auctions, hammer prices have shown an increase, which could indicate growing interest in this coin.

Based on these factors, an estimated maximum purchase price for this coin could be between 90 and 120 euros. This is based on the average hammer price and the condition rating, as well as the price trend in recent auctions. However, the final price will depend on the competition in the auction and the interest of other bidders.