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

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

2. Historical Prices: By looking at previous auction prices for coins with similar conditions, we can see that:
- In past auctions, coins with a condition of 70 have reached hammer prices of up to 135 euros.
- The general trend shows that hammer prices have fluctuated, but overall, coins with a condition of 70 have had a range between 130 and 160 euros.

3. Starting Price and Average Hammer Price: The current starting price is 120 euros, and the average hammer price for this coin in the past has been 157.66 euros. This suggests that the hammer price could be above the starting price.

4. Recent Trends: In the most recent auctions, the hammer price has been 160 euros for a coin with a condition of 80, indicating that there is interest in quality coins.

Based on these factors, an estimated maximum purchase price for the coin with a condition of 70 could be in the range of 150 to 180 euros. This takes into account the starting price, the condition, and historical hammer prices.

Therefore, a reasonable maximum purchase price could be 170 euros.