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

1. Current Condition: The coin has a condition of 70 (MS-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Previous Prices: By observing the auction prices of coins with similar conditions (around 70-80), we can see that they have reached auction prices ranging from 60 to 155 euros. For example:
- In 2018, a coin with a condition of 70 was auctioned for 95 euros.
- In 2021, a coin with a condition of 80 was auctioned for 110 euros.
- In 2022, a coin with a condition of 75 was auctioned for 110 euros.

3. Average Auction Price: The average auction price for this coin is 94.08 euros, which also provides us with a reference.

4. Starting Price: The starting price is 65 euros, indicating that the seller expects a reasonable price for the auction.

5. Sales Trends: The coin has been sold in 24 out of the last 27 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be in the range of 100 to 120 euros, considering that the condition is good and there are precedents of successful sales in that range. Therefore, a reasonable maximum purchase price could be 120 euros.