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

1. Condition: The coin to be auctioned has a condition of 70 (MBC-). This is slightly lower than previous coins that have sold, which have a condition of 80. This could influence the price, as lower condition generally means a lower price.

2. Previous Prices: Previous auction prices for coins with a condition of 80 have been in a range of approximately 200 to 220 euros. Since the condition of the current coin is lower, it is reasonable to expect that the auction price will be somewhat lower.

3. Starting Price and Average Hammer Price: The starting price is 200 euros, and the average hammer price in the past has been 210.67 euros. This suggests that the hammer price could be in a similar range.

4. Auction Trends: Given that this coin has a history of successful sales (sold 6 times out of 6 auctions), this indicates a consistent interest in the coin, which could help maintain the price.

Taking all these factors into account, an estimated maximum purchase price could be around 200-210 euros, considering that the condition is a limiting factor. However, given the interest in the coin and the price history, a reasonable maximum purchase price could be approximately 210 euros.