To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Current Condition: The coin has a condition of 80 (MBC+), indicating that it is in quite good shape. This suggests that its value should be in the upper range of previous auction prices.

2. Previous Auction Prices:
- In 2020, with a condition of 80, it was auctioned for 1300 euros.
- In 2019, with a condition of 75, it was auctioned for 240 and 185 euros.
- In 2016, although the condition is not specified, it was auctioned for 1600 euros.
- In 2014, it was auctioned for 950 euros with an unspecified condition.

3. Price Trends: The average auction price is 1959.44 euros, indicating that, in general, coins of this reference tend to reach high prices at auctions.

4. Current Starting Price: The starting price is 750 euros, which is relatively low compared to previous auction prices.

5. Estimation: Given that the condition of the coin is good (80) and considering the previous auction prices, a reasonable maximum purchase price could be in the range of 1300 to 1600 euros, based on the highest auction price of 1300 euros in a similar condition and the auction of 1600 euros in a similar context.

Therefore, an estimated maximum purchase price for this coin could be 1600 euros.