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

1. Current Condition: The coin has a condition 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 of similar coins in the past has been 849.85 euros.
- In previous auctions, coins with a similar condition (70 and 75) have reached hammer prices that varied, but some examples are:
- 1200 euros (2022, condition 70)
- 2100 euros (2023, condition 85)
- 850 euros (2020, condition 80)
- The trend shows that coins with a condition of 70 have had hammer prices ranging between 600 and 1200 euros.

3. Starting Price and Average Starting Price:
- The current starting price is 600 euros, which is a good starting point.
- The average starting price of 479.46 euros suggests that the current starting price is competitive.

4. Demand and Supply: The coin has been auctioned 27 times in the past, with a sell-through rate of 96.3% (26 out of 27). This indicates a consistent interest in this coin.

Based on these factors, an estimated maximum purchase price could be between 1000 and 1200 euros, considering that the condition is slightly lower than the coins that have reached higher prices, but still, the interest and sales history suggest it could fetch a good price at auction.

Therefore, a reasonable maximum purchase price could be 1100 euros.