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. Starting Price and Average Hammer Price: The starting price is 90 euros, and the average hammer price in previous auctions is 117 euros. This suggests that, in general, coins of this reference tend to sell for above their starting price.

3. Sales History: The coin has been auctioned 67 times, of which 62 have been sold. This indicates good demand and a history of successful sales.

4. Previous Prices: Looking at previous hammer prices for coins with similar grades, we can see that they have reached hammer prices that varied considerably, but some relevant examples are:
- In 2019, a coin with a grade of 70 sold for 70 euros.
- In 2018, a coin with a grade of 80 sold for 82 euros.
- In 2022, a coin with a grade of 75 sold for 120 euros.

5. Recent Trends: In the most recent auctions, hammer prices have shown a range from 94 euros to 180 euros for similar grades.

Based on these factors, an estimated maximum purchase price could be in the range of 120 to 150 euros, considering that the grade of 70 is a limiting factor, but that the sales history and demand are positive. Therefore, a reasonable maximum purchase price could be 150 euros.