To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the starting price, the average hammer price, and previous prices from similar auctions.

1. Current starting price: 180 euros.
2. Average hammer price: 171.18 euros.
3. Coin condition: 70 (VF-), which is an acceptable but not excellent condition.
4. History of prices from previous auctions:
- Most previous auctions with a condition of 70 have had hammer prices ranging from 130 to 190 euros.
- In auctions with similar conditions, the hammer price has reached up to 190 euros.

Given that the coin has a condition of 70 and considering the starting price of 180 euros, which is slightly higher than the average hammer price, we can estimate a maximum purchase price.

Based on the price history and the condition, a reasonable maximum purchase price could be in the range of 190 to 210 euros, considering that the highest hammer price in the past for a similar condition was 190 euros and that the current starting price is 180 euros.

Therefore, an estimated maximum purchase price could be 200 euros. This allows for some margin for competition in the auction, while also staying within the limits of what has been previously paid for coins in similar conditions.