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 70 (VF-), indicating that it is in relatively good shape, but not among the best qualities.

2. Auction History:
- The average hammer price for similar coins has been 76.7 euros.
- In previous auctions, hammer prices have varied significantly, with some reaching up to 400 euros in superior conditions (such as in the auction on 2022-03-17 with a condition of 95).
- The majority of hammer prices for similar conditions (70) have been in a range of 20 to 101 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 12 euros, which is quite low compared to the average starting price of 40.64 euros.

4. Sales Trends: The coin has been sold in 22 out of 25 auctions, indicating good demand.

Based on these factors, an estimated maximum purchase price could be set in a range between 70 and 100 euros, considering that the condition is 70 and the average hammer price has been 76.7 euros.

Therefore, a reasonable maximum purchase price could be 90 euros. This allows for a margin for competition in the auction, as the hammer price may vary depending on demand at the time of the auction.