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 75 euros, and the average hammer price in previous auctions is 86.89 euros. This suggests that, on average, similar coins have sold for above the starting price.

3. Sales History: The coin has been auctioned 163 times, of which 144 have been successful sales. This indicates good demand and consistent interest in this reference.

4. Previous Prices: By looking at the hammer prices of coins with a similar condition (80) in the past, we can see that they have reached hammer prices that vary, but some have reached up to 140 euros (for example, in auctions from 2019).

5. Recent Trends: In the most recent auctions, hammer prices for coins of similar condition have been in the range of 100 to 150 euros.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 100 to 130 euros. This is based on the hammer price history and the current condition of the coin. However, given that interest in the coin appears to be strong, a price of up to 150 euros could be reasonable considering the competition in the auction.