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

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. Previous Prices: By observing previous auction prices for coins with similar conditions (70-85), we can see that:
- In past auctions, coins with a condition of 70 have reached hammer prices of up to 270 euros.
- Coins with a condition of 80 have reached hammer prices of up to 950 euros, but this is an exceptional case.

3. Starting Price and Average Hammer Price: The current starting price is 150 euros, and the average hammer price in the past has been 344.85 euros. This suggests there is potential for an increase in the hammer price.

4. Auction Trends: The coin has been auctioned 26 times, of which 22 have sold. This indicates good demand and sustained interest in the coin.

5. Previous Estimates: The average starting price of 193 euros and the average hammer price of 344.85 euros also suggest that the hammer price could be significantly higher than the starting price.

Taking all these factors into account, an estimated maximum purchase price for this coin could be in the range of 300 to 400 euros, considering that the condition is a limiting factor and that interest in the coin appears to be strong. A hammer price of around 350 euros could be a reasonable target, given the price history and current condition.