To estimate a maximum purchase price for the coin that will be auctioned, we will consider several factors:

1. Condition of the coin: The coin in question has a condition rating of 100 (MS), indicating that it is in excellent condition. This generally translates to a higher price compared to coins with lower conditions.

2. Starting price: The starting price is 200 euros. This is the baseline for the auction.

3. Historical data:
- The average hammer price for similar coins is 74.27 euros, but this may not be representative due to the high condition of the coin in question.
- In previous auctions, we have seen hammer prices that varied significantly, with some reaching up to 380 euros for coins in similar conditions.

4. Price trends: In past auctions, coins with a condition rating of 100 have achieved hammer prices that exceed the starting price. For example, in the December 2021 auction, a coin with a condition rating of 100 was sold for 380 euros.

5. Market expectations: Given the significant interest in high-condition coins and the fact that it has been auctioned 77 times in the past, there is likely to be an active market for this coin.

Taking all these factors into account, an estimated maximum purchase price could be between 300 and 400 euros, considering that the condition is excellent and there are precedents for high prices in previous auctions. However, the final price will depend on the competition in the auction and the interest of collectors.