To estimate a maximum purchase price for the coin in question, we can consider several factors based on the provided data:

1. Coin Condition: The coin has a condition rating of 70 (MBC-). This indicates that it is in an acceptable state, but not of high quality. Coins with a higher condition rating tend to fetch higher prices at auctions.

2. Starting Price and Previous Prices: The current starting price is 70 euros, and the average hammer price in previous auctions is 135.49 euros. This suggests that, in general, coins of this reference tend to sell for a significantly higher price than their starting price.

3. Auction History: The coin has been auctioned 229 times, of which it has sold 209 times. This indicates good demand and liquidity in the market for this coin.

4. Previous Hammer Prices: Looking at previous hammer prices for coins with a similar condition (70), we can see that they have reached hammer prices that vary, but some have reached 150 euros or more in similar conditions.

5. Recent Trends: In the most recent auctions, the hammer prices have shown a range that suggests interest in this coin may be increasing, especially considering that the average hammer price is 135.49 euros.

Based on these factors, an estimated maximum purchase price for this coin could be between 150 and 180 euros. This is based on the history of hammer prices and the current condition of the coin. However, it is important to note that the final price may vary depending on competition in the auction and the interest of collectors at that time.