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 100 (S/C), indicating that it is in excellent condition. This generally increases its value compared to coins with lower conditions.

2. Auction history:
- The average hammer price for this coin is 30.68 euros, suggesting that, in general, coins of this reference have sold for relatively low prices.
- However, there have been recent auctions where higher prices have been reached, such as the hammer price of 180 euros in May 2024 for a coin with unspecified condition, indicating that there is potential for value increase.

3. Starting price and previous prices:
- The current starting price is 30 euros, which is quite low compared to the average hammer price.
- In previous auctions, the hammer price has varied, but there are examples where prices of 45 euros and 65 euros have been reached for similar conditions.

4. Market trends: Given that the coin will be auctioned in the coming days and has a history of successful auctions, it is reasonable to assume that interest could be high, especially due to its good condition.

Taking all these factors into account, an estimated maximum purchase price could be between 50 and 70 euros. This is based on the potential of the coin's condition and market interest, as well as previous hammer prices. However, it is important to stay alert to the dynamics of the auction and the competition from other bidders.