To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the condition of the coin.

1. Previous Auction Data:
- The coin has been auctioned 16 times, of which it has sold 15 times.
- The average hammer price in previous auctions is 104.13 euros.
- Previous hammer prices varied, but there are examples of hammer prices reaching up to 245 euros in an auction with a condition of 90.

2. Condition:
- There is no information about the condition of the current coin, which complicates the estimation a bit. However, we can observe that in previous auctions, coins with conditions ranging from 70 to 90 have had hammer prices ranging from 36 to 245 euros.

3. Starting Price:
- The current starting price is 150 euros, which is higher than the average starting price of 60.87 euros in previous auctions. This could indicate that the coin has a higher perceived value or that it is expected to reach a higher hammer price.

4. Estimation:
- Given that the average hammer price is 104.13 euros and considering that the starting price is 150 euros, it is reasonable to assume that the hammer price could be in a higher range due to demand or the quality of the coin.
- Based on previous hammer prices and the starting price, an estimated maximum purchase price could be between 150 and 200 euros, considering that the starting price is an indicator of the sellers' expectations.

Therefore, an estimated maximum purchase price for this coin could be 200 euros.