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 of 80 (MBC+), indicating that it is in relatively good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Previous Prices: By looking at previous auction prices for coins with similar conditions (80-85), we can see that auction prices have varied, but there are examples of auctions reaching up to 150 euros. For example:
- In 2020, a coin with a condition of 80 was auctioned for 80 euros.
- In 2019, a coin with a condition of 85 was auctioned for 120 euros.
- In 2023, a coin with a condition of 95 was auctioned for 300 euros, indicating that the value can increase significantly with better condition.

3. Average Auction Price: The average auction price for this coin is 155.08 euros, suggesting that, in general, buyers are willing to pay close to this price.

4. Starting Price: The starting price is 70 euros, which is relatively low compared to previous auction prices.

5. Sales Trends: The coin has been auctioned 60 times, of which 55 have sold, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 150 to 200 euros, considering that the condition is good and the average auction price is 155 euros. However, since the coin has a condition of 80, a more conservative price could be around 150 euros, while a more optimistic buyer might be willing to pay up to 200 euros if demand is high at the auction.

Therefore, a reasonable estimated maximum purchase price could be between 150 and 200 euros.