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

1. Coin Condition: The coin to be auctioned has a condition of 70 (MBC-). This is an important factor, as coins in better condition tend to fetch higher prices.

2. Previous Prices: By looking at the hammer prices of coins with a similar condition (70) in previous auctions, we can see that:
- In the auction on 2020-10-20, a coin with a condition of 70 was sold for 21 euros.
- In the auction on 2018-12-11, another coin with a condition of 70 was sold for 13 euros.
- In the auction on 2022-10-19, a coin with a condition of 85 (slightly better) was sold for 190 euros.

3. Average Hammer Price: The average hammer price for this coin is 96.47 euros, indicating that, in general, coins of this reference tend to reach higher prices.

4. Starting Price and Estimates: The starting price is 12 euros, and the average starting price is 53.07 euros. This suggests that the hammer price could be significantly higher than the starting price.

5. Auction Trends: Given that there have been 76 auctions of this coin and 69 have resulted in sales, there is good demand for this coin.

Based on these factors, an estimated maximum purchase price for the coin in question could be in the range of 70 to 100 euros, considering that condition is a key factor and that the average hammer price is 96.47 euros.

Therefore, a reasonable maximum purchase price could be 100 euros.