To estimate a maximum purchase price for the coin in question, we can analyze the provided data, especially the previous auction prices and the current condition of the coin.

1. Condition: The coin has a condition of 80 (MBC+), indicating that it is in quite good shape. This is important because coins in better condition tend to fetch higher prices at auctions.

2. Previous auction prices:
- In previous auctions, we have seen hammer prices that vary, but there are several examples of coins with similar condition (80) that have sold for prices ranging between 340 and 420 euros.
- The highest hammer price for a coin with condition 80 was 420 euros.

3. Average hammer price: The average hammer price for this coin is 299 euros, suggesting that, in general, buyers are willing to pay around this amount.

4. Starting price: The starting price of 600 euros is relatively high compared to previous hammer prices, which could indicate that the seller expects a higher price due to demand or the quality of the coin.

5. Auction trends: Given that the coin has been auctioned 14 times and has sold 9 of those times, there is a consistent interest in this coin, which may influence the price.

### Estimation of the maximum purchase price:
Taking all these factors into account, a reasonable maximum purchase price could be in the range of 400 to 450 euros. This is based on the highest hammer price observed for coins of similar condition and the general interest in the coin.

Therefore, an estimated maximum purchase price could be 450 euros.