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. Previous Prices: Looking at previous auction prices for coins in similar condition (80), the hammer price has ranged between 810 and 1300 euros. A condition rating of 80 is higher than 70, so it is reasonable to expect that the hammer price for the coin in question will be lower than that of coins with a condition rating of 80.

3. Starting Price and Average Hammer Price: The current starting price is 1550 euros, which is significantly higher than the average hammer price of 1016.11 euros. This suggests that the seller has high expectations, but the market may not be willing to pay that much.

4. Auction Trends: The coin has been auctioned 9 times and has sold on all occasions, indicating consistent interest in the coin. However, the average hammer price is a good indicator of what buyers are willing to pay.

Taking all these factors into account, an estimated maximum purchase price could be around 1000-1100 euros. This is based on the average hammer price of coins in similar condition and the fact that the condition of this coin is lower than those that have sold in the past at higher prices.

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