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-), 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:
- The average hammer price for similar coins in the past is 47 euros.
- The coin has been auctioned 22 times, of which it has sold 18 times, indicating good demand.
- Previous hammer prices for coins with a similar condition (70) have ranged between 30 and 115 euros, with a more common hammer price around 40-70 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 25 euros, which is below the average starting price of 34.94 euros. This suggests there is potential for an increase in the hammer price.

4. Recent Trends: In the most recent auctions, hammer prices for coins with a condition of 70 have been in the range of 40-70 euros.

Based on these factors, an estimated maximum purchase price could be in the range of 60-70 euros, as this price reflects both the condition of the coin and the historical hammer prices in previous auctions. However, it is important to consider that the final price may vary depending on the competition in the auction and the interest of other buyers.