To estimate a maximum purchase price for the coin that will be auctioned, we will consider several factors, including the starting price, the auction price history of similar coins, and the lack of information regarding the condition of the coin in question.

1. Starting Price: 150 euros.
2. Auction Price History:
- In previous auctions, the hammer prices have varied considerably. For example, hammer prices of 60, 190, 220, 350, and even 460 euros have been recorded for coins with different levels of preservation.
- The general trend shows that hammer prices can be significantly higher than the starting price, especially for coins that have had good interest in the past.

3. Condition: The lack of information about the condition of this coin may be a limiting factor. However, since similar coins have sold in the range of 150 to 460 euros, we can infer that there is high auction potential.

4. Analysis of Past Sales:
- The average hammer price for similar coins is approximately 98.9 euros, but there are examples of much higher hammer prices, suggesting that interest can be variable.
- Given that there are 2 auctions scheduled in the coming days, this could increase competition and interest in the coin.

Estimated Maximum Purchase Price:
Taking into account the starting price of 150 euros and the auction price history, a reasonable maximum purchase price could be between 300 and 400 euros, depending on the competition in the auction and the interest of collectors. This is based on the fact that hammer prices can be double or more than the starting price in competitive auctions.

Therefore, an estimated maximum purchase price could be 400 euros.