To estimate a maximum purchase price for the coin in question, we can analyze the provided data, including the starting and hammer prices from previous auctions, as well as the condition of the coin.

1. Current starting price: 700 euros.
2. Average hammer price in the past: 896.41 euros.
3. Hammer price history:
- Hammer prices have varied, with some reaching up to 2200 euros in recent auctions.
- Most hammer prices fall between 500 and 1200 euros, depending on the condition.

4. Condition: There is no specific information about the condition of this coin, but in previous auctions, coins with a condition rating of 70 to 85 have reached hammer prices between 1200 and 2100 euros.

5. Trends:
- The general trend shows that coins of similar condition have had hammer prices that exceed the starting price.
- The last auction of a similar coin reached a hammer price of 1500 euros with a starting price of 900 euros.

Based on this data, an estimated maximum purchase price could be in the range of 1200 to 1500 euros, considering that the hammer price can be significantly higher than the starting price, especially if the condition is favorable.

Therefore, a reasonable estimated maximum purchase price could be 1500 euros.