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

1. Current Condition: The coin has a condition of 80 (MS+). 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 with similar conditions:
- In 2023, a coin with a condition of 80 sold for 1400 euros.
- In 2021, a coin with a condition of 80 sold for 1300 euros.
- In 2020, coins with a condition of 85 sold for 1200 euros.

3. Starting Price and Average Hammer Price: The current starting price is 1200 euros, and the average hammer price in the past has been 1210 euros. This suggests that the starting price is reasonable and that there is a good chance it will be met or exceeded.

4. Auction Trends: Since the coin has been auctioned 10 times and all have sold, this indicates a consistent interest in the coin, which may positively influence the price.

5. Maximum Price Estimate: Based on previous hammer prices and the current condition, a maximum purchase price could be between 1400 and 1500 euros. This is because the highest hammer price for a similar condition was 1400 euros, and considering the possibility that interest in the coin could lead to a slightly higher price.

Therefore, an estimated maximum purchase price for this coin could be 1500 euros.