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. Starting Price and Average Hammer Price: The starting price is 60 euros, and the average hammer price in previous auctions is 84.01 euros. This suggests that, on average, similar coins have reached prices above the starting price.

3. Sales History: The coin has been auctioned 89 times, of which 84 have been successful sales. This indicates good demand and consistent interest in this reference.

4. Previous Prices: By looking at previous hammer prices for coins with similar conditions (around 80), we can see that they have reached hammer prices that varied, but some have reached 110 euros in the case of coins with higher conditions.

5. Recent Trends: In the most recent auctions, hammer prices have shown an increase, which could indicate an upward trend in the value of this coin.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 120 euros. This is based on the good condition of the coin, the hammer price history, and the trend of increasing value. Therefore, a reasonable maximum purchase price could be 110 euros.