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

1. 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 is 164.17 euros.
- In the past, there have been auctions where the coin has sold for significantly higher prices, such as 700 euros in an auction in 2018 with a condition rating of 95.
- Most of the time, the hammer price has been above the starting price, indicating consistent demand.

3. Starting Price and Previous Prices:
- The current starting price is 70 euros, which is reasonable given the price history.
- The average starting price of 66.11 euros suggests that the current starting price is aligned with past trends.

4. Supply and Demand: Since it has been auctioned 8 times in the past and sold 6 of those times, there is interest in this coin.

Based on these factors, an estimated maximum purchase price could be slightly higher than the average hammer price, considering the condition and demand.

Estimated Maximum Purchase Price: 200 euros.

This price reflects a balance between the coin's condition, price history, and market demand.