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

1. Coin Condition: The coin has a condition rating of 70 (MBC-), indicating that it is in an acceptable state, but not among the best qualities.

2. Current Price and Previous Prices: The current starting price is 60 euros. In previous auctions, the average hammer price has been 73.87 euros, suggesting that coins of similar condition have reached prices above the starting price.

3. Auction History: The auction history shows that coins with a condition rating of 70 have had hammer prices that varied, but some have reached up to 75 euros in the past. However, there are also examples of coins with similar conditions that have sold for less.

4. Price Trends: The average hammer price of 73.87 euros and the fact that there have been 87 sales of this coin in the past indicate a consistent interest in this coin, which may increase its value at auction.

Considering these factors, an estimated maximum purchase price could be around 80 euros. This price reflects a balance between the condition state, historical interest in the coin, and the average hammer price in previous auctions.