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:
- The average hammer price in previous auctions is 32.2 euros.
- The coin has been auctioned 31 times, of which it has sold 15 times. This suggests that there is moderate interest in the coin.
- Previous hammer prices for coins with similar conditions (80) have varied, but there are examples of auctions reaching up to 80 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 35.53 euros. This could indicate a good buying opportunity.

4. Recent Trends: In the most recent auctions, hammer prices have been in the range of 20 to 40 euros for similar conditions.

Based on these factors, an estimated maximum purchase price could be in the range of 50 to 70 euros. This is based on historical interest, current condition, and average hammer price. However, since the starting price is low, it may be possible to acquire it for a price closer to the lower end of this range.

Therefore, a reasonable estimated maximum purchase price could be 60 euros.