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 quite good shape. This is important because coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for this coin in the past has been 1229.43 euros.
- In previous auctions, hammer prices have varied, but there are examples of hammer prices exceeding 1600 euros (such as in 2016).

3. Starting Price: The current starting price is 700 euros, which is relatively low compared to the average hammer price.

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

5. Previous Auction Prices:
- In 2020, it was auctioned with a starting price of 700 euros and an estimated price of 900 euros, but it did not sell.
- In 2018, with a starting price of 400 euros, it sold for 440 euros, showing that interest may be increasing.

Given all this, an estimated maximum purchase price could be positioned in a range between the average hammer price and the highest estimated price from previous auctions.

Estimation: Considering the average hammer price of 1229.43 euros and the price history, a reasonable maximum purchase price could be approximately 1300 to 1500 euros. This reflects interest in the coin and its condition, as well as the price trends in previous auctions.