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

1. Starting price: 800 euros.
2. Average hammer price in the past: 1400 euros. This indicates that, although the starting price is 800 euros, the final price at which it has sold in the past is significantly higher.
3. Condition of the coin: 80 (MBC+). This suggests that the coin is in good condition, which may increase its value compared to coins in lower condition.
4. Auction history: The coin has been auctioned once and sold on that occasion, indicating that there is interest in it.

Given that the average hammer price is 1400 euros and considering that the condition is good, an estimated maximum purchase price could be in a range between the starting price and the average hammer price.

Taking these factors into account, an estimated maximum purchase price could be around 1200 to 1300 euros. This reflects an interest in the coin, but also a margin of safety in case the demand is not as high as in the previous auction.