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

1. 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. Current and previous prices: The current starting price is 675 euros. In previous auctions, we have seen hammer prices that vary, but there are examples of hammer prices exceeding 700 euros, especially for coins in similar or better conditions.

3. Price trends: Looking at previous hammer prices for coins with a condition of 80, the highest hammer price was 700 euros, while other hammer prices in similar conditions have ranged from 600 to 800 euros.

4. Average hammer price: The average hammer price for this coin is 627 euros, suggesting that the market is willing to pay around this amount on average.

5. Auction expectations: Since there are no auctions scheduled in the coming days, this could increase interest in the current coin, potentially leading to a higher hammer price.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 800 euros. This price reflects both the good condition of the coin and the price trends observed in previous auctions.