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 80 (MBC+), indicating that it is in relatively good shape. This suggests that its value should be above coins in worse conditions.

2. Current Starting Price and Previous Prices: The current starting price is 1100 euros, and the average starting price in previous auctions is 3076.18 euros. This indicates that the current starting price is significantly lower than the historical average, which could represent a good buying opportunity.

3. Previous Hammer Prices: The average hammer price in previous auctions is 5461.79 euros. This suggests that, in general, coins of this reference tend to sell for much higher prices than the current starting price.

4. Sales Trends: Out of the 10 times it has been auctioned, it has sold 7 times, indicating good demand for this coin.

5. Comparison with Previous Prices: In the 2022 auction, a coin with a condition rating of 85 sold for 2400 euros. This suggests that a coin with a condition rating of 80 could have an estimated value in a similar range, although slightly lower.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 2400 to 3000 euros, considering that the condition is slightly lower than that of the coin that sold for 2400 euros and that the current starting price is quite low compared to the historical average.

Therefore, a reasonable maximum purchase price could be 2500 euros.

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

1. Condition: The coin to be auctioned has a condition of 70 (MS-). This is an important factor, as coins in better condition tend to fetch higher prices.

2. Previous Prices: By observing the hammer prices of coins with similar conditions, we can see that:
- In 2011, a coin with a condition of 75 sold for 336 euros.
- In 2012, the same condition (75) reached a price of 750 euros.
- In 2020, a coin with a condition of 70 sold for 100 euros.
- In 2022, a coin with a condition of 80 sold for 300 euros.

3. Starting Price and Average Prices: The starting price of the coin is 650 euros, and the average hammer price in previous auctions is 417.11 euros. This suggests that the starting price is relatively high compared to the average hammer price.

4. Sales Trends: The coin has been auctioned 12 times in the past, of which it has sold 8 times. This indicates that there is interest in the coin, but also that there is a 33% chance it has not sold, which may influence the perception of its value.

Taking all these factors into account, an estimated maximum purchase price could be in the range of 400 to 600 euros, considering that the starting price is 650 euros and the average hammer price is 417.11 euros. However, given that the condition is 70, which is lower than other coins that have sold for higher prices, a reasonable maximum purchase price could be approximately 550 euros. This allows for some competition in the auction, but also reflects the reality of the market based on historical data.