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 (MBC-). This is an important factor, as coins in better condition tend to reach higher prices.

2. Auction History:
- The average hammer price of similar coins in the past is 3936.17 euros.
- The average starting price is 2649.42 euros.
- Previous auctions of this coin have shown hammer prices that vary significantly, from low prices (such as 439.99 euros) to higher prices (such as 12834.03 euros).

3. Price Trends:
- Coins with higher conditions (such as 80 or 90) have reached significantly higher hammer prices. For example, a coin with a condition of 90 has sold for over 6000 euros on several occasions.
- A condition of 70 is lower than many of the coins that have sold for high prices, suggesting that the price of this coin will not reach those levels.

4. Starting Price: The starting price is 800 euros, indicating that the seller has expectations of a minimum price.

Based on these factors, an estimated maximum purchase price for this coin could be in the range of 1500 to 2500 euros, considering that the condition is not the best and that the price history shows significant variations. A hammer price around 2000 euros could be a reasonable target, given the auction history and current condition.