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. Previous Auction Prices: By looking at previous auction prices for coins with a similar condition (80), we can see that they have reached auction prices of up to 250 euros in the past (as seen in the auction on December 16, 2020).

3. Starting Price and Average Hammer Price: The current starting price is 200 euros, and the average hammer price in the past has been 183.72 euros. This suggests that the starting price is reasonable and could attract bidders.

4. Recent Trends: In the most recent auctions, hammer prices for coins with similar conditions have ranged from 180 to 240 euros, indicating sustained interest in this type of coin.

5. Auction Expectations: Since it will be auctioned in the coming days, bidders may be willing to pay a little more due to competition.

Taking all these factors into account, an estimated maximum purchase price could be around 250-270 euros. This is based on the highest hammer price observed for coins of similar condition and the trend of prices in recent auctions.