To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Current Grade: The coin has a grade of 70 (MS-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Current Starting Price and Previous Prices: The current starting price is 75 euros. In previous auctions, the average hammer price has been 159.17 euros, indicating that coins of this reference usually sell for significantly higher prices than their starting price.

3. Sales History: The coin has been auctioned 96 times, of which 91 have resulted in sales. This suggests high demand and an active market for this coin.

4. Previous Hammer Prices: Looking at previous hammer prices for coins with a similar grade (70-75), we can see that they have reached hammer prices that vary, but some have reached 110 euros or more in similar conditions.

5. Recent Trends: In the most recent auctions, hammer prices have shown a trend of being higher, especially for coins in similar condition grades.

Based on these factors, an estimated maximum purchase price for this coin could be between 120 and 150 euros. This is based on the history of hammer prices and the current grade of the coin. However, since the market can be volatile, it is advisable to keep an eye on the auction and consider the competition from other bidders.