To estimate a maximum purchase price for the coin in question, we can analyze the provided data:

1. Current starting price: 60 euros.
2. Current grade: 70 (MBC-), which is a relatively good grade, although not the best.
3. Auction history:
- The average starting price in the past has been 103.96 euros.
- The average hammer price has been 142.56 euros.
- In previous auctions, hammer prices have varied considerably, with some reaching very high prices (for example, 304.96 euros in 2016).

4. Price trends:
- The coin has been auctioned 14 times, of which it has sold 11 times, indicating good demand.
- The last auction in which the coin was sold was at 70 euros, which may be an indicator of its current value.

5. Comparison with coins of similar grade:
- In previous auctions, coins with a similar grade (75) have sold for prices ranging from 70 to 111.65 euros.

Given that the grade of the coin is 70 and considering the price history, an estimated maximum purchase price could be in a range between the average hammer price (142.56 euros) and the highest recorded hammer price (304.96 euros), adjusted for the grade.

Final estimate: A reasonable maximum purchase price could be around 120-150 euros, taking into account the grade and price history. This allows for a margin for competition in the auction, while also remaining within a realistic range based on historical data.