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

1. Current Condition: The coin has a condition of 70 (MS-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price for coins of this reference is 2433.33 euros.
- In the past, coins with similar conditions (70 and 75) have had hammer prices that varied, but generally, the hammer prices have been in a range that may be indicative of what can be expected.

3. Starting and Hammer Prices:
- The coin has a starting price of 1500 euros, which is lower than the average starting price of 1850 euros. This could indicate a buying opportunity.
- In previous auctions, hammer prices have varied considerably, but there are examples of coins with similar conditions that have reached hammer prices of up to 3000 euros.

4. Recent Trends:
- In the most recent auction, a coin with a condition of 70 sold for 1700 euros, which may be a good indicator of the current market value.

Taking all these factors into account, an estimated maximum purchase price for this coin could be around 2000-2500 euros. This is based on the history of hammer prices and the current condition of the coin. However, it is important to consider that the final price may vary depending on demand at the auction and other market factors.