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

1. Current Condition: The coin has a condition rating of 70 (VF-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for similar coins in the past has been 1,035.94 euros.
- Previous auctions of this same coin have shown hammer prices that vary, but some have reached up to 3,900 euros in similar conditions (75 condition).
- The last auction of this coin with a condition of 70 had a hammer price of 400 euros, indicating that the market may be fluctuating.

3. Starting Price and Average Starting Price:
- The current starting price is 400 euros, and the average starting price in the past has been 528.87 euros. This suggests that the current starting price is reasonable, but there may be room for an increase.

4. Market Trends:
- Given that there has been consistent interest in this coin (33 out of 36 auctions have resulted in sales), this suggests that there is demand.

Based on these factors, an estimated maximum purchase price could be in the range of 1,000 to 1,200 euros, considering that the condition is a limiting factor and that the average hammer price is significantly higher. However, given the history of hammer prices, it is possible that a buyer may be willing to pay more if competition is high during the auction.

Therefore, a reasonable maximum purchase price could be 1,200 euros.