To estimate a maximum purchase price for the coin in question, let's consider several factors:

1. Starting price: 2000 euros.
2. Current grade: 75 (MS), which is a fairly good grade.
3. Auction history:
- In 2021, a coin with a grade of 70 sold for 950 euros.
- In 2022, a coin with a grade of 80 sold for 1700 euros.

4. Average hammer price: 2083.33 euros, indicating that, in general, coins of this reference tend to reach higher prices at auction.

Given that the current grade of the coin (75) is better than the coin auctioned in 2021 (70) and slightly lower than the one from 2022 (80), we can infer that the hammer price should be in an intermediate range between 1700 euros and 2083.33 euros.

Considering the starting price of 2000 euros and the price history, an estimated maximum purchase price could be around 1800-2000 euros, as the starting price is a good indicator of what buyers are willing to pay.

Therefore, an estimated maximum purchase price could be 2000 euros.