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

1. Current Condition: The coin has a grade of 70 (VF-), indicating that it is in acceptable condition, but not among the best.

2. Auction History:
- The average hammer price in previous auctions is 168.04 euros.
- The coin has been auctioned 28 times, of which it has sold 27 times, indicating good demand.
- In previous auctions, hammer prices for coins with a similar grade (70) have varied, but there are examples of sales reaching up to 170 euros.

3. Starting Price and Estimates:
- The current starting price is 150 euros, which is slightly higher than the average starting price of 92.17 euros, suggesting that the seller has high expectations.
- The estimated price for this auction is 250-300 euros, which also indicates that considerable interest is expected.

4. Recent Trends: In recent auctions, hammer prices exceeding 200 euros have been observed for coins in similar conditions.

Based on these factors, an estimated maximum purchase price could be around 200-220 euros. This is based on the hammer price history for coins of similar condition and the price trend in recent auctions. However, since the starting price is 150 euros, some bidders may be willing to pay a little more, but not much beyond this range, considering the coin's condition.