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

1. Current Condition: The coin has a condition rating of 80 (MS+), indicating 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 from previous auctions is 1355.1 euros.
- The last auction with a hammer price was 1600 euros, suggesting that there is growing interest in this coin.
- The most recent auction with a similar condition (80) had a hammer price of 1600 euros.

3. Starting Price and Estimates:
- The current starting price is 1200 euros, which is reasonable given the hammer price history.
- The average starting price in the past has been 1125 euros, indicating that the current starting price is slightly higher than average, but not excessively so.

4. Market Trends:
- The coin has been auctioned 14 times, of which 12 have sold, indicating good demand.
- There are no auctions scheduled in the near future, which could increase competition among current bidders.

Based on these factors, an estimated maximum purchase price could be around 1600-1800 euros, considering that interest in the coin seems to be increasing and that the condition is favorable. However, it is important to keep in mind that the final price will depend on the competition in the auction and the willingness of other bidders to pay.