To estimate a maximum purchase price for the coin that is going to be auctioned, we can analyze the provided data. Here are some key points to consider:

1. Starting Price: The starting price of the current auction is 150 euros.
2. Auction History: The coin has been auctioned 44 times in the past, with a total of 38 sales. This indicates that there is considerable interest in the coin.
3. Previous Prices: Previous hammer prices varied, but there are examples of hammer prices reaching up to 600 euros in recent auctions (such as in June 2022).
4. Condition: There is no information about the condition of this particular coin, which may complicate the estimation. However, it can be observed that in previous auctions, coins with conditions of 90 and 95 have reached hammer prices of 200 and 600 euros, respectively.

Given that the starting price is 150 euros and considering the history of hammer prices, an estimated maximum purchase price could be in the range of 200 to 300 euros, depending on the demand in the auction and the quality of the coin.

Therefore, an estimated maximum purchase price could be 250 euros. This is based on the analysis of previous hammer prices and the interest in the coin.