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. Condition: The coin to be auctioned has a condition of 75 (MS). This is an important factor, as coins in better condition tend to reach higher prices.

2. Previous auction prices: Looking at the auction prices of coins with similar conditions:
- In 2021, a coin with a condition of 75 was auctioned for 1400 euros.
- In 2022, another coin with a condition of 70 was auctioned for 900 euros.
- In 2021, a coin with a condition of 85 was auctioned for 2000 euros.

3. Average auction price: The average auction price for coins auctioned in the past is 1098.13 euros, indicating that, in general, coins of this reference tend to reach significant prices.

4. Starting price: The starting price of 600 euros is reasonable, but given the history of auction prices, it is likely that the final price will be considerably higher.

Taking all these factors into account, an estimated maximum purchase price for the coin in question could be between 1200 and 1500 euros, considering that the condition is good and there is a history of auction prices that supports this estimate.