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

1. Current Condition: The coin has a condition of 80 (MS+), which indicates that it is in quite good shape. This generally translates to a higher price compared to coins with lower conditions.

2. Auction History: By looking at previous auction prices, we can see that coins with similar conditions have reached varying hammer prices. For example:
- In 2018, a coin with a condition of 85 was sold for 90 euros.
- In 2014, a coin with a condition of 80 was sold for 40 euros.
- In 2021, a coin with a condition of 80 was sold for 70 euros.

3. Average Hammer Price: The average hammer price for this coin is 50.89 euros, which can also serve as a reference.

4. Starting Price: The starting price is 35 euros, indicating that the seller expects a reasonable minimum price.

Taking these factors into account, an estimated maximum purchase price could be between 70 and 90 euros, given that the condition is good and there are precedents for sales in that range for coins of similar condition.

Therefore, an estimated maximum purchase price could be 80 euros.