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

1. Current Condition: The coin has a condition of 70 (VF-), indicating that it is in an acceptable state, but not excellent. This may influence the price, as coins in better condition tend to fetch higher prices.

2. Auction History:
- The average starting price from previous auctions is 360.71 euros, and the average hammer price is 415 euros.
- Previous auctions show hammer prices that vary, but generally, the hammer prices have been significantly higher than the starting price.

3. Price Trends:
- In previous auctions, hammer prices have ranged from 170 euros to 800 euros, depending on the condition and other factors.
- The last auction with a similar condition (70) had a hammer price of 320 euros.

4. Current Starting Price: The starting price is 80 euros, which is relatively low compared to previous hammer prices.

Given all this, an estimated maximum purchase price could be set in a range that considers the average hammer price and the current condition.

Estimation: We could estimate a maximum purchase price around 350-400 euros, taking into account that the condition is not the best and that the starting price is low, but also considering the hammer price history that suggests the coin could reach a higher price at auction.